Sonic Generations

"3 Eras, 2 Sonics, 1 Epic adventure!"

- Tagline

Sonic Generations (ソニック ジェネレーションズ) is a platformer game for Xbox 360, PlayStation 3, Nintendo 3DS and PC via download. The game was made to celebrate the 20th anniversary of the Sonic the Hedgehog series. The Japanese version has different subtitles: White Time and Space (白の時空) for the home consoles, and Blue Adventures (青の冒険) for the 3DS version. This game can be played in 3D on the 3DS and on the console versions also, but a 3DTV as well as a pair of 3D glasses are required for the PS3 and Xbox 360. It uses stereoscopic 3D with the involvement of a pair of screens in one.

Development
The PS3/360/PC version of the game was in development since Sonic Unleashed, four years prior.

In late 2010, rumors of a Sonic Anniversary game surfaced online. The rumors told of a game that would potentially feature remakes of levels from throughout Sonic's history. The game was alleged to be released on all major game consoles at the time: PSP, PS3, Xbox 360, Wii, and DS.

In early 2011, Sonic Generations was finally announced for the PS3 and Xbox 360. Later, a Gamestop release list printed on May 7, 2011 showed a 3DS port of Generations with a tentative release date of 12/31/11. Speculation was rife about the existence of such a version. Later in the month, a Sega-Sammy earnings report listed 3DS and PC versions of the game; however, a revised version of the report no longer listed either version. The June issue of Nintendo Power confirmed Sonic Generations (3DS). It contained an in-depth preview and interview with Takashi Lizuka.

Lizuka said that the 3DS edition would only feature Sonic's friends "who are integral to the story"&mdash;a contrast from the console counterparts. He also stated that the 3DS version could possibly use some handheld game stages while the console versions would only use stages from the console main series. "For the PS3 and 360, none of the stages we're selecting are going to be from the handheld." Iizuka said. "However, on 3DS we're looking at picking stages from handheld as well." The 3DS had minor story changes as well. The writers for the story are credited as Ken Pontac and Warren Graff of Happy Tree Friends fame. They also worked on Sonic Colors and MadWorld. Tetsu Katano, who directed Sonic and the Black Knight and did work on the Adventure series, directed the 3DS edition. Like Sonic Colors (DS), Sonic Team and Dimps co-developed the 3DS edition.

The PC version was confirmed in early October.

Console/PC
The story takes place shortly after Sonic's last encounter with Eggman in Sonic Colors. In the past of Green Hill, Classic Sonic is exploring when he hears a noise. He then looks around and shrugs, thinking it was nothing. Suddenly, the Time Eater appears in the sky and he notices it, as the screen goes white. In the present day, Tails and the rest of Sonic's friends are having a surprise birthday party for the blue hedgehog, which is quickly ruined when the Time Eater appears again and sucks all of them back into different periods of Sonic's history. Sonic tries to attack the Time Eater but is easily knocked to the ground by a swipe of its arm, and blacks out. Tails is the only one left struggling to resist the Time Eater's vortex, but his grip soon slips and he is pulled in. Sonic wakes from his unconsciousness in a white world with a colorless Green Hill Zone and wonders what's going on. Sonic first frees Tails when he is in a frozen state. Sonic and Tails then decide on finding their friends. Tails then tells Sonic to go check Chemical Plant out. Sonic quickly sets off, but a few seconds later, Tails sees Classic Sonic and mistakes him for Modern Sonic.

After Sonic brings Chemical Plant back to normal and saves Amy, Tails reaches Sonic and explains how he would never forget the Chemical Plant's smell, and the annoying pink acid the place is filled with. Sonic agrees and tells Tails that the place is giving him déjà vu. Meanwhile, Classic Sonic encounters Metal Sonic guarding a Chaos Emerald, battles him at the bad future of Stardust Speedway, and destroys him. Later, after restoring Sky Sanctuary and rescuing Knuckles, Modern Sonic is in a black and white hall with a large glass panel with Classic Sonic at the other side of the glass. Modern Sonic mistakes it for a mirror, along with mistaking Classic Sonic as his reflection, and vice versa. The two start setting their hair and looking at their teeth, concerned about their looks. When the two Sonics touch their bellies, Modern Sonic noticed how his reflection's belly is rounder, and gets the feeling that the reflection is not him. The two then hear Classic Dr. Eggman's voice, with Modern Sonic shouting his name; Classic Sonic looks at his Modern self through the glass and realizes that it was not his reflection the whole time. Classic Sonic runs towards Classic Eggman's voice. Modern Sonic is surprised to see his "reflection" running while he isn't, and realizes that his "reflection" is actually Classic Sonic. Modern Sonic tries to catch up to Classic Sonic, but the door closes on him before he can enter, resulting in him being locked in the room.

Finding himself in the Death Egg, Classic Sonic goes exploring but finds himself at a ledge, and falls back with relief. Then the Death Egg Robot rises up in front of him, starting a battle. After the Death Egg battle, he sees the Time Eater kidnapping Classic Dr. Eggman, while the Classic villain ironically cries for help. Modern Sonic sees his Classic self as he returns and is in disbelief that there is another Sonic. Modern and Classic Tails tell the Sonics that they are traveling through time and space, which is why they are experiencing all of their past encounters, along with seeing Classic Sonic. The two Sonics quickly team up and run towards the remaining zones to restore their color and their natural place in time. The two realize that the faster they go through the zones, the more time and color will be restored.

After the Dreamcast Era, comprised of Speed Highway, City Escape, and Seaside Hill, and saving Cream, Cheese, Rouge, and Espio, Modern Sonic finds Shadow near City Escape. Shadow tells Sonic he doesn't care where he is; he just wants to finish their battle. Sonic accepts and the two battle on in Final Rush. Sonic defeats Shadow with the help of some power cores. Later, while Classic Sonic was in Seaside Hill, Modern Sonic finds himself in a flooded Station Square. the city starts to rumble and Perfect Chaos comes out and starts screaming. He then opens his eyes, spots Sonic, and the battle begins. After the battle, Perfect Chaos drowns (somehow Sonic is able to defeat him without Super Transformation). After Perfect Chaos, the gang has a little chat until Time Eater appears leaving 3 more zones in the white limbo. After leaving the third zone, Time Eater spots a colorless Chaos Emerald and tries to attack it, but the power of the Chaos Emerald blocks it off. The two Sonics restore Crisis City, rescuing Blaze. Modern Sonic then finds Silver above Crisis City. Silver is surprised to see him, and thinks he is a faker because he hasn't seen him in a long time. Silver challenges him to a battle in Crisis City. Modern Sonic rushes to the scene of the battle and joins in, eventually managing to defeat Silver.

After restoring Rooftop Run and rescuing Vector and left with only one more place to bring back, the two Tails realize that the Time Eater dislikes Chaos Emeralds and tell the two Sonics to collect the seven Emeralds. The two Sonics restore Planet Wisp and saving Charmy the two Sonics race each other to the Emerald. Modern Sonic beats Classic Sonic in the race because he's had more experience (using the Sonic Boost in the air, which impresses Classic Sonic). After beating the Egg Dragoon, Classic Sonic is confused to see Modern Eggman inside of it, as he thought that Eggman got kidnapped. However, the Time Eater comes again and kidnaps Eggman once again, leaving the entire gang confused.

The gang then chases after the Time Eater and find it to be a supernatural being converted to a machine being piloted by Modern and Classic Dr. Eggman. When asked, Modern Eggman explains that while he was trapped in space with Orbot and Cubot at the end of Sonic Colors, he found a monster with a unique ability to erase time and space. His plan was to undo all of his past mistakes whilst kidnapping Sonic's friends to use as bait to get Sonic to chase after him. (Though Modern Eggman left Cubot and Orbot in Space.) He also had the help of Classic Eggman in order for all of it to work. The monster tries destroying the two Sonics; though they put up a decent fight, it quickly manages to knock them to the ground and crush them with its arm. The two Sonics pass out, but before they can be finished off, they get support from all of their friends along with Shadow and Silver, allowing the Chaos Emeralds to glow and activate, transforming them into Super Sonics. The two defeat the Eggmen and their monster, and return back to where Sonic had his birthday party.

At the party, Modern Sonic gets to enjoy the rest of his chili dog, which was blown away by the Time Eater's interruption of his birthday party, as Classic Sonic and the rest of the gang reappear, including Shadow and Silver. After a few conversations between the two Sonics and two Tails, Classic Sonic tries out Sonic Boost in the air but fails to perform it properly, falling down and landing on his head. Modern Sonic claps for Classic Sonic anyway, saying that he's only going to get better. Modern Sonic and Tails share a few high-fives and wave good-bye as Classic Sonic and Tails jump back to their time-line through a portal.

A post-credits scene shows the two Eggmen lost in the white space. The two argue as they search for an exit, discuss whether or not they ever defeat Sonic and contemplate if they should go back and get their teaching degree as opposed to continuing their misdeeds.

Handheld
The story begins with Classic Sonic in Green Hill. After completing Act 1, a purple vortex in the sky appears and surprises Classic Sonic. After that, it goes all the way to the present day and Sonic is invited to a birthday party by Tails. However, Sonic arrives early, so Tails tells him to wait. But then a vortex sucks Tails into it. Sonic jumps in but is "attacked", though he manages to get in anyway. Sonic sees a white world and wonders what's going on. Modern Sonic rescues Tails after restoring Green Hill, and Tails tells him that he sees a big city in nighttime and a giant mushroom, so Sonic decides to go check those places out, being followed by Classic Sonic, who is believed by Tails to be Modern Sonic.

After restoring Casino Night, Tails informs Sonic that he feels like he has been there and Sonic mentions that he had a some sort of déjà vu of that place too. After restoring all of the zones in the Classic Era, the Boss Gate opens and Sonic enters it. He then sees Classic Sonic through a glass, thinking that it's a mirror. Then, both Sonics hear Eggman's voice, and Classic decides to follow the voice through a portal, but Modern was unable to get there in time. After entering the portal, Classic Sonic meets with Metal Sonic and races him. After winning, Classic Sonic meets with Classic Eggman on his giant robot, the Big Arm. After the boss fight with the Big Arm, Classic Eggman is kidnapped by the Time Eater and the 2 Sonics and the 2 Tails meet. The Tails' explain that they're traveling through time and space. Classic Sonic then learns the Homing Attack after Modern Sonic used it on some Spinners.

After clearing the Adventure Era, which is comprised of Emerald Coast, and Radical Highway, the Sonics go to the boss gate and Modern Sonic tells Classic Sonic that he's going to take care of it. After beating both Shadow and the Biolizard, Tails does some modifications to Modern Sonic's shoes so he can do the Stomp.

After the DS Era, comprised of Water Palace and Tropical Resort, Sonic meets with Silver, and then Modern Eggman again on his Egg Emperor. After the fight, Eggman is kidnapped by the Time Eater again.

After restoring all the levels and collecting the Chaos Emeralds, the Sonics go to fight the Time Eater who turned out to be some sort of monster being controlled by both Classic and Modern Eggman, and from seeing both Tails defend the Sonics from the monster, the Chaos Emeralds allow the Sonics to go Super.

After defeating the Time Eater, both Sonics and Tails return to the place where the party was going to take place, and Modern Sonic starts eating his chilli dog. However, Classic Tails realizes that the vortex to the past was closing, so he and Classic Sonic had to go back. Just before leaving, Classic Sonic shows Modern that he's learning the Boost as well. After telling him to have a great future, Modern Sonic says goodbye to Classic Sonic and he, along with Classic Tails, return to the past.

Sonic Boom
A Sonic Generations demo was playable at 2011's E3 Expo, under the name "Sonic Boom". It was the first major American Sonic event, being hosted by SEGA, and took place on June 8th, at 6pm PT. At E3, Sonic Generations was playable in both console and handheld versions. Although only Green Hill was playable for the console versions, City Escape was shown; Green Hill was playable, including the boss Big Arm, was playable for the 3DS version. There was also a Birthday Song for Sonic sung at Sonic Boom and the ending of the song, "Happy Birthday Sonic!" will appear in Sonic Generations. This song appeared at the Tokyo Joypolis event and at the Summer of Sonic event in London. It appeared at the Gamescon 2011 event in Germany, and at TGS (Tokyo Game Show) 2011.

Demo Release
The Australian government’s OFLC rated a multi-platform demo release of Sonic Generations, and SEGA formally announced at E3 that they would release a demo for PSN and Xbox Live on Sonic's 20th Anniversary, June 23rd. The demo only contained Green Hill, and only the Classic Sonic playthrough. However, this demo also contained many unused files that revealed much about the full game, notably the stage list. The demo was only available until July 12th, at which point it was no longer available, including for players who had already downloaded it; the file essentially locked itself. In the Xbox Live version, one has to be an Xbox Live Gold Member to download the demo. The name of the demo is "Sonic Generations Green Hill Zone Demo #1", indicating another demo was on the way. SEGA confirmed on their blog a second demo released in Europe for PSN and Xbox Live on October 18th and was released in North America for PSN on October 25th. The demo contains both classic and modern Sonic playable in Green Hill Zone, and has no time limit.

Gameplay
The game features levels derived from 20 years of Sonic history, ranging from the Classic era, through the Dreamcast era, to the Modern era. There is a level taken from each mainstream Sonic game to represent the different times. Each level can be played with either Classic Sonic or Modern Sonic, each taking their own routes throughout the level. Classic Sonic's levels are strictly two-dimensional side-scrolling stages, using classic moves like the Spin Attack and the Spin Dash. Modern Sonic's levels, on the other hand, carry on the modern 2-D/3-D gameplay of recent titles such as Sonic Unleashed and Sonic Colors, featuring Homing Attacks, Combo Tricks in the air, Drift, the Stomp Attack, Light Speed Dash, and Speed Boosts. Red rings from Sonic Colors return in the console version. Five can be found in each Act, and collecting them unlocks extras, such as music, art, and movies.

Hub worlds like the ones in Sonic Unleashed were confirmed in an interview with Takashi Iizuka. He said that the hub world starts out as the white space, but opens up more as the Sonics pass through more levels. The Hub worlds are only playable in 2D, so they are not free roam like they were in Unleashed. One character is rescued in each stage. Characters rescued will stand outside the entrance to the stage, and they can be talked to. Also, there is an area above the entrance to the main stages where the player can access extra missions and rival battles. Bosses are accessed through special areas known as "Boss Gates", found at the end of each era.

The handheld version, unlike the console versions, makes the Modern Sonic gameplay similar to Sonic Rush, while also featuring Special Stages based on Sonic Heroes. Some bosses are played as Classic Sonic and some are played as Modern Sonic. This game, like most other Sonic games, features acts, with Act 1 played as Classic Sonic and Act 2 played as Modern Sonic, along with 10 missions per level.

Classic Sonic
Classic Sonic stages consist of him running in a permanent 2-D perspective, platforming all the way towards an end sign post just like in the original games. Patrick Riley referred to Classic Sonic levels as "Momentum-Based Platforming". He can also use the Spin Dash.

The handheld 3DS version uses stereoscopic 3-D to give a sense of depth. Classic Sonic also has an unlockable homing attack in both versions.

Modern Sonic
Modern Sonic's console stages consist of running extremely fast through the stages while the perspective switches between 2-D and 3-D such as in his more recent games, Sonic Unleashed (PS3/360, daytime levels) and Sonic Colors (Wii version) specifically.

The player can perform Combo Tricks, which can be used to fill up the boost gauge, by using special objects. There is a new visual element to all returning levels such as the cave in Green Hill. There's a bit more platforming involved like the sections after the cave in Green Hill. The camera is also immovable unlike in Sonic Unleashed and invisible walls can hinder the exploration aspect.

In the handheld version, Modern Sonic's gameplay is similar to Sonic Rush and Sonic Colors (DS version). He has the Sonic Boost, the ability to slide under obstacles, jump off walls, and use the Homing Attack. After the Dreamcast Era, Modern Sonic learns the Stomp. Modern Sonic's levels use the 3-D effect of depth on the handheld version more actively as well as to giving a better view for when Modern Sonic jumps into the background, although the console versions are 3-D TV compatible. In the PS3, 360 and PC versions, Modern Sonic is only able to wall jump off of certain panels (similar to the DS version of Sonic Colors), while in the 3DS version he is able to jump off of any wall (much like Sonic Unleashed and the Wii version of Sonic Colors).

Genesis/MegaDrive
The original Sonic the Hedgehog game from 1991 is available to unlock in the console versions only. To play the game, the player has to buy the "Sega Genesis/Mega Drive Controller" for 7777 skill points from the Skill Shop.

Profile Card (3DS version)
The profile card is a feature in the 3DS version. It shows the player's user name, their rank (from Beginner to Grand Master), how many years have passed since they became a Sonic fan, their favorite Sonic game, as well as their favorite character, their Mii, and the points it has. On the back (the player can turn the card by pressing the R button), it shows the progress they had in the story, how much they had unlocked in the Collection Room, how many missions they had unlocked, how many rings had been collected, their play time, and all of the ranks the player has achieved on the levels.

The player can also unlock card patterns for it by leveling up the card. They were taken from different Sonic games, including all the ones that are represented in Generations. There are patterns of games such as Sonic 3D Blast, Sonic Spinball, Sonic the Fighters, Sonic Riders and Shadow The Hedgehog. Some of Sonic's transformations, such as Excalibur Sonic and the Werehog, receive a card pattern.

When a card is leveled up 2 ranks, the card changes to a new color. For example, when a card is Rank Beginner (2nd lowest rank), the card's color is yellow, but if the player reaches the next rank (Intermediate), the card turns orange. Once the player has reached the Grand Master Rank, the card turns silver and has a shining effect. When the player reaches the final rank, Legendary (999999 points), the card turns golden and has sparkles around it.

The ranks are:
 * Novice (Yellow)
 * Beginner (Yellow)
 * Intermediate (Orange)
 * Skilled (Orange)
 * Advanced (Red)
 * Expert (Red)
 * Pro (Blue)
 * Master (Blue)
 * Grand Master (Silver)
 * Legendary (Golden)

Versus Mode (3DS version)
There is local wireless and Wi-Fi 2-player race mode in the 3DS version of the game. In the multiplayer mode, the player can use Download Play to send a signal to another 3DS user (though both players must have a copy of the game), or the player can challenge the world by using the Wi-Fi connection. There are also online leaderboards between their races and world-wide races. By playing online races, one can earn points and card patterns for their profile card, and after playing more online races, the player can unlock extra content in the collection room, as well as some of the 100 extra missions.

Also by playing online races, the player can obtain a special skill to use in the main game (the player can only get one skill per day). The skills are:
 * 10 Rings
 * Standard Shield
 * Thunder Shield
 * Invincibility
 * Bomb

To use a skill, the player must press the L button or touch the skill icon on the touch screen.

StreetPass (3DS version)
StreetPass is used to unlock special content and challenges, and is activated when someone with a 3DS passes by someone else with a 3DS. The player can also use the Nintendo 3DS "Playcoins" system to buy content such as missions (which cost five Playcoins each) in case one is unable to StreetPass (the player can also unlock content by playing online). With StreetPass, the player can trade their profile card as well as adding three missions to exchange with other players. Once the player StreetPasses somebody, their profile card gets upgraded in various ways.

30-second Trial (Console/PC version)
In this mode, the player has to get as far as they can in a stage in 30 seconds. They can upload your score online and see who of their friends made it the farthest in one specific level.

Time Attack
In this mode, the player can see how fast they can clear a stage, a rival or a boss fight and share their time in online leaderboards. In the 3DS version, all stages can be played for a top time, and 300 Supporter Points (for the player's profile card) are awarded for each time submitted to the leaderboards. In the 360/PS3 version, Time Attack can only be done online, and only the 18 Main Acts can be played for a top time.

Playable

 * Sonic the Hedgehog (Both Classic and Modern)
 * Super Sonic (Both Classic and Modern)

Friends

 * Miles "Tails" Prower (Both Classic and Modern)
 * Knuckles the Echidna (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Amy Rose (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Cream the Rabbit (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Rouge the Bat (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Vector the Crocodile (Console/PC version) (indirectly mentioned in 3DS version ) (Cameo too)
 * Espio the Chameleon (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Charmy Bee (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Blaze the Cat (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)

Supporting

 * Omochao (Optional guide) (Console/PC)
 * Cheese the Chao (Follows Cream) (Console/PC) (Cameo in 3DS version)
 * Chao (They appear in a Speed Highway mission)
 * Animal friends (Flickies and other species must be rescued)
 * Orange Wisp (Console power-up for Modern Sonic)
 * Pink Wisp (Console power-up for Classic Sonic)
 * Red Wisp (3DS power-up for Classic Sonic)
 * Cyan Wisp (3DS power-up for Modern Sonic)

Cameos

 * Fang the Sniper - City Escape (Wanted poster)
 * Bean the Dynamite - City Escape (Wanted poster)
 * Bark the Polar Bear - City Escape (Wanted poster)
 * Mighty the Armadillo - City Escape ("Missing since 1993" poster)
 * Ray the Flying Squirrel - City Escape ("Missing since 1993" poster)
 * Chao - Speed Highway/City Escape/Crisis City/Radical Highway ("Chao in Space" billboard in Speed Highway, "Chao in Space 2" billboard in City Escape, "Chao in Space 3" for Crisis City, "Chao in Space 4" in Speed Highway's hub world section and a neon sign for Radical Highway) & Trophy room
 * Perfect Chaos - City Escape ("Chao in Space 2", also a boss)
 * Big the Cat - Casino Night (neon sign) & Trophy room
 * E-123 Omega - Speed Highway (road sign) & Trophy room
 * Death Egg Robot - Speed Highway ("Chao in Space" billboard in Speed Highway)
 * Tikal - Speed Highway ("Chao in Space: The Search For Tikal" billboard)
 * Chip - Speed Highway (road sign) & Trophy room
 * Jet the Hawk - Speed Highway (road sign) & Trophy Room
 * Wave the Swallow - Speed Highway (road sign)
 * Storm the Albatross - Speed Highway (road sign)
 * NiGHTS - Radical Highway (NiGHTS hotel [3DS version only])
 * Orbot & Cubot - (Eggman mentions that he left them in space after the events of Sonic Colors; current status unknown)
 * White Wisps - Planet Wisp (In the beginning of both acts)
 * Mii - Profile Card, Wi-fi Icon.

Enemies

 * Dr. Eggman (Both Classic and Modern; arch-rivals of Sonic(s))

Console/PC

 * Motobug - Green Hill
 * Giant Motobug - Green Hill (mission)
 * Chopper - Green Hill/Seaside Hill
 * Big Chopper - Green Hill/Seaside Hill
 * Crabmeat - Green Hill/Planet Wisp
 * Buzz Bomber - Green Hill
 * Buzzer - Green Hill
 * Giant Buzz Bomber - Green Hill (mission)
 * Spiny - Chemical Plant
 * Grabber - Chemical Plant
 * EggRobo - Sky Sanctuary
 * Cop Speeder - Speed Highway
 * Mono Beetle - City Escape
 * Gun Beetle - City Escape
 * Gun Hunter - City Escape
 * Egg Pawn - Seaside Hill/Planet Wisp
 * Spinner - Seaside Hill/Speed Highway/Planet Wisp
 * Electro Spinner - Seaside Hill/Speed Highway/Planet Wisp
 * Iblis Biter - Crisis City
 * Iblis Taker - Crisis City
 * Iblis Worm - Crisis City
 * Egg Fighter - Rooftop Run
 * Egg Launcher - Rooftop Run
 * Aero Chaser - Rooftop Run
 * Aero-Cannon - Rooftop Run
 * Sandworm - Planet Wisp
 * Buzzer - Planet Wisp

Nintendo 3DS

 * Motobug - Green Hill
 * Chopper - Green Hill
 * Crabmeat - Green Hill
 * Buzz Bomber - Green Hill
 * Newtron - Green Hill
 * Crawl - Casino Night
 * Butterdroid - Mushroom Hill
 * Mushmeanie - Mushroom Hill
 * Dragonfly - Mushroom Hill
 * Madmole - Mushroom Hill
 * Baby Kiki - Emerald Coast
 * Rhino-Tank - Emerald Coast
 * Sweeper - Emerald Coast
 * Mono Beetle - Radical Highway
 * Gold Beetle - Radical Highway
 * Gun Hunter - Radical Highway
 * Blue Eagle GUN Plane - Radical Highway
 * Egg Flapper - Water Palace
 * Knight Pawn - Water Palace
 * Klagen - Water Palace
 * Egg Pawn - Tropical Resort
 * Spinner - Tropical Resort

Rivals

 * Classic Metal Sonic - Stardust Speedway/ Casino Night
 * Shadow the Hedgehog - Final Rush / Radical Highway
 * Silver the Hedgehog - Crisis City / Tropical Resort

Console/PC Exclusive

 * Death Egg Robot - Death Egg
 * Perfect Chaos - Station Square
 * Egg Dragoon - Eggmanland

Nintendo 3DS Exclusive

 * Big Arm - Launch Base
 * Biolizard - Cannon's Core
 * Egg Emperor - Final Fortress

Final Boss

 * Time Eater - Center of Time

Items

 * Rings
 * Red Star Rings
 * Item boxes
 * 10 rings boxes
 * Invincibility (Classic only in Console/PC version, both in 3DS version)
 * Shield (clear in Console/PC version, green in 3DS version)
 * Elemental Shields (Fire, Lightning, and Bubble) (lightning shield only for 3DS version)
 * Speed Sneakers (Console/PC version)
 * Extra Life
 * Skateboard (Classic Sonic only, Console/PC version)
 * Wisps (Sealed in Wisp Capsules) (Orange and Pink Wisps in PS3/360/PC Version and Cyan and Red Wisps in 3DS Version)
 * Bomb (3DS version)
 * Chaos Emeralds
 * Boss Gate Keys (Console/PC version)
 * Media (Music, Art, and Videos)

Voice Actors
Classic Sonic is silent throughout the game, but still shows his personality through his actions and gestures. Aaron Webber mentioned in an interview, that if anyone were to be Classic Sonic, it would be Jaleel White. Aaron had to make a choice whether Classic Sonic would be voiced by Jaleel White or have no voice at all. Aaron also mentioned that he grew up with the classic cartoons of Sonic like Adventures of Sonic the Hedgehog, and he thought Jaleel White did a fantastic job.

Voice overs exist not only for English and Japanese, but for German, French, Italian, and Spanish.

Soundtrack
The soundtrack for Sonic Generations is called "Blue Blur: Sonic Generations Original Soundtrack" which includes the Soundtrack for both the HD and 3DS versions of Sonic Generations.

The music in the game was remixed by Jun Senoue and Tatsuya Kozaki, with guest remixes done by Tomoya Ohtani, Kenichi Tokoi and Naofumi Hataya (who remixed the classic versions of the Genesis stage themes), among others. The hub world themes for the stages either use a violin or a flute remix, except Speed Highway, which uses the same theme as the original and Planet Wisp, which is a techno remix.


 * Green Hill: Remix of Green Hill Zone from the original Sonic the Hedgehog. The classic remix is similar to the original tune, but with a techno beat. Modern is a much more rock-based theme, with two different versions used dependent on how fast Sonic is going at the time. Extra drums are added with the boost.
 * Chemical Plant: Remix of Chemical Plant Zone from Sonic the Hedgehog 2. The classic remake is almost identical with a techno beat. The modern remix is slower and is more of a soft rock. *
 * Sky Sanctuary: Remix of Sky Sanctuary Zone from Sonic & Knuckles. The classic remix-as expected-is a nearly the same with a techno beat. The modern remake is a soothing-almost relaxing remix, but still retains a fast pace. As with Green Hill, Modern Sky Sanctuary has two versions dependent on how fast Sonic is going. Extra drums are added when Modern Sonic uses his boost. *
 * Speed Highway: Remix of the first section of Speed Highway from Sonic Adventure. The classic remake has a techno beat. The modern tune is very similar to the original, but has a heavier use of the guitar. The 'Going Down' remix plays in the Modern skyscraper section. *
 * City Escape: Remake of City Escape from Sonic Adventure 2. The classic remix has a techno beat and traces of the Endless Mine Zone theme. The modern remake is nearly identical, but has some traces of Sonic's theme song "It Doesn't Matter". The song itself is called "Escape from the City". The 'Mad Convoy Race' remix plays at the end of the Modern act.*
 * Seaside Hill: Modern is a mixture of a rock remix of both the original Seaside Hill and Ocean Palace, classic only has Seaside Hill, but is a dance remix and a better use of the guitar. *
 * Crisis City: Modern has a violin based remix that is close to the original with a faster beat; Classic has a heavy rock and techno remix of the original but it still sounds similar. This track was remixed by Tomoya Ohtani, who was responsible for the original track. *
 * Rooftop Run: Modern is based on the original theme, with some violin modifications and a new piano introduction. Classic has a disco-style remix. This track was remixed by Tomoya Ohtani, who was responsible for the original track. *
 * Planet Wisp: Modern has a Drum and Piano remix which sounds like the original's Act 1 whilst Classic has a Heavy Guitar and Techno remix that sounds similar to Sonic CD's bad future themes. Kenichi Tokoi remixed both the classic and modern tracks. *
 * Casino Night: It's a jazz-like remix of Casino Night Zone from Sonic the Hedgehog 2. In the 3DS Version, Classic has original with some beat ** and Modern has a Jazz Remix.
 * Mushroom Hill: Classic has the original with some beat and Modern has some heavy metal guitar and piano. **
 * Emerald Coast: Classic is remix of Azure Blue World. Modern is a remix of "Windy and Ripply." **
 * Radical Highway: Classic and Modern remix of "Vengeance is Mine." **
 * Water Palace: Classic has the original "Back 2 Back." whilst modern has a Funky Rock remix.**
 * Tropical Resort: Modern is a faster, guitar rock remix of the original Tropical Resort Act 1 theme, classic is identical to the original Tropical Resort. **
 * Hub Worlds: Separate violin renditions of each stage's music are played in the Hub of that Zone, with the exception of Speed Highway. *
 * Metal Sonic Rival Battle: Almost the same as the original Stardust Speedway (Bad Future) from the Japanese/PAL soundtrack, with parts of the normal Stardust Speedway theme included. The US version of the theme is a techno remix.
 * Death Egg Robot Battle: Orchestral version of the final boss of Sonic the Hedgehog 2. *
 * Shadow Rival Battle: Remix of For True Story from Sonic Adventure 2.
 * Vs. Perfect Chaos: Remix of "Open Your Heart" from Sonic Adventure. It has an added beat and slightly heavier bass. Circuit Freq remixed the track with Jun Senoue providing a new guitar performance. *
 * Vs. Perfect Chaos (Pinch): Re-orchestrated version of the music used in the second round of the battle against Perfect Chaos. *
 * Silver Rival Battle: Remix of Vs. Character theme from Sonic the Hedgehog (2006).
 * Egg Dragoon Battle: Remix of the Final Battle in Sonic Unleashed. *
 * Big Arm Battle: (3DS) Remix of the Final Boss theme for Sonic the Hedgehog 3, rendered by Alex Makhlouf of Cash Cash. **
 * VS. Biolizard: Remix of "Supporting Me." **
 * VS. Egg Emperor: Remix of Emperor from Sonic Heroes. **
 * Menu: Rendition of the Sonic Heroes Menu Theme. **
 * Loading Screen: Remix of the saving center in Eggman's Metropolis from Sonic Chronicles: The Dark Brotherhood. *
 * Invincibility: For both Modern and Classic, this is a remix based off the original Sonic the Hedgehog 2 Invincibility theme. The Modern remix is only present in the 3DS version.
 * Speed Shoes: For Classic Sonic only, when the stage's original music is played, the music speeds up. If a different music track is played, the Sonic Adventure (1 & 2) Speed Shoe track plays.﻿
 * Time Break: Slower paced remix of Cyber Track from Sonic Advance 3 and also includes parts of the Chaos Control jingle (Boss ver.) from Shadow The Hedgehog. This was not in the final version of the game.
 * Game Over: Remix of the game over theme from Sonic the Hedgehog 3
 * Special Stage: (3DS) is a remix of the Special Stage from Sonic Heroes. **
 * Super Sonic: Remix of the introduction to "Live and Learn" and the Invincibility theme from Sonic 4.
 * Co-op Mission/Ring Collector: Remix of Balloon Park from Sonic 3 & Knuckles multiplayer mode.
 * Race Mission/Keep the Pace: Pop and techno remix of "Super Sonic Racing" from Sonic R. 
 * 'VS Mission/Defeat the Enemies Metal Remix of Emerald Beach from Sonic Battle.
 * Help Mission/Special Trial Remix of Title from Sonic 3D Blast.
 * Compete Mission/Stealth Attack Remix of Quick Race from Sonic Heroes.
 * Skill Shop: Remix of the results screen from Sonic the Hedgehog 2. 
 * Collection Room: Violin rendition of "Door into Summer" from Knuckles Chaotix. *
 * Media Select: Violin rendition of the data select from Sonic 3 & Knuckles. 
 * Network: Remix of the title theme from Sonic Mega Collection.
 * End Medley: Medley of every stage from the game, containing slightly modified versions of the original themes of each stage, similar to "Medley Rush" from Sonic Rush. It starts off and ends like in the ending theme of Sonic the Hedgehog (1991). There are two versions of the ending medley. One plays on the 360/PS3/PC version while the other version plays on the 3DS version.
 * Title theme: Remix of title theme from Sonic the Hedgehog.
 * Level Clear: Level Clear theme since Sonic 3 up till Sonic 06.

Unlockable Music
Music can be unlocked by completing some missions or collecting a number of red star rings. The player can view their music by going to the collection room and they can use music for stages. There is a total of 50 unlockable songs in the Console and PC versions, which are:
 * "Green Hill Zone (Original)" (Sonic the Hedgehog)
 * "Marble Zone" (Sonic the Hedgehog)
 * "Star Light Zone" (Sonic the Hedgehog)
 * "Emerald Hill Zone" (Sonic the Hedgehog 2)
 * "Chemical Plant Zone (Original)" (Sonic the Hedgehog 2)
 * "Special Stage" (Sonic the Hedgehog 2)
 * "Angel Island Zone" (Sonic the Hedgehog 3)
 * "Hydro City Zone" (Sonic the Hedgehog 3)
 * "Marble Garden Zone" (Sonic the Hedgehog 3)
 * "Mushroom Hill" (Sonic and Knuckles)
 * "Flying Battery Zone" (Sonic and Knuckles)
 * "Death Egg Zone" (Sonic and Knuckles)
 * "Open Your Heart" (Sonic Adventure)
 * "It Doesn't Matter" (Sonic Adventure)
 * "Emerald Coast" (Sonic Adventure)
 * "Metal Harbor" (Sonic Adventure 2)
 * "Live & Learn" (Sonic Adventure 2)
 * "Green Forest" (Sonic Adventure 2)
 * "Special Stage - Bonus Challenge" (Sonic Heroes)
 * "Sonic Heroes" (Sonic Heroes)
 * "What I'm Made Of..." (Sonic Heroes)
 * "His World" (Sonic 06)
 * "Wave Ocean" (Sonic 06)
 * "Kingdom Valley" (Sonic 06)
 * "Endless Possibility" (Sonic Unleashed)
 * "Windmill Isle - Day" (Sonic Unleashed)
 * "Savannah Citadel - Day" (Sonic Unleashed)
 * "Reach for the Stars" (Sonic Colors)
 * "Tropical Resort" (Sonic Colors)
 * "Sweet Mountain" (Sonic Colors)
 * "Toxic Caves" (Sonic Spinball)
 * "Palmtree Panic - Present (Japanese Soundtrack)" (Sonic CD)
 * "Sonic Boom" (Sonic CD)
 * "Stardust Speedway (US)" (Sonic CD)
 * "Diamond Dust Zone" (Sonic 3D Blast)
 * "Super Sonic Racing" (Sonic R)
 * "Neo Green Hill Zone" (Sonic Advance)
 * "Leaf Forest" (Sonic Advance 2)
 * "Route 99" (Sonic Advance 3)
 * "Right There, Ride On" (Sonic Rush)
 * "A New Venture" (Sonic Rush Adventure)
 * "High Flying Groove" (Sonic Riders)
 * "Un-Gravitify" (Sonic Riders: Zero Gravity)
 * "Free" (Sonic Free Riders)
 * "Quick Trip To Paradise" (Sonic Rivals)
 * "Race To Win" (Sonic Rivals 2)
 * "I Am... All of Me" (Shadow the Hedghog)
 * "Let the Speed Mend It" (Sonic and the Secret Rings)
 * "Knight of the Wind" (Sonic and the Black Knight)
 * "Splash Hill Zone " (Sonic the Hedgehog 4)

The 3DS version also has 50 unlockable songs, which can be heard in the collection room (even when the 3DS is closed with headphones connected to it, working like a MP3 player) These songs are unlockable rewards for completing the missions:
 * "Green Hill Zone" (Sonic the Hedgehog)
 * "Marble Zone" (Sonic the Hedgehog)
 * "Star Light Zone" (Sonic the Hedgehog)
 * "Emerald Hill Zone" (Sonic the Hedgehog 2)
 * "Chemical Plant Zone (Original)" (Sonic the Hedgehog 2)
 * "Special Stage" (Sonic the Hedgehog 2)
 * "Angel Island Zone" (Sonic the Hedgehog 3)
 * "Hydro City Zone" (Sonic the Hedgehog 3)
 * "Marble Garden Zone" (Sonic the Hedgehog 3)
 * "Mushroom Hill" (Sonic and Knuckles)
 * "Flying Battery Zone" (Sonic and Knuckles)
 * "Death Egg Zone" (Sonic and Knuckles)
 * "Open Your Heart" (Sonic Adventure)
 * "Believe In Myself" (Theme of Tails) (Sonic Adventure)
 * "My Sweet Passion" (Theme of Amy) (Sonic Adventure)
 * "Live and Learn" (Sonic Adventure 2)
 * "Unknown From M.E." (Theme of Knuckles) (Sonic Adventure 2)
 * "Throw It All Away" (Theme of Shadow) (Sonic Adventure 2)
 * "Sonic Heroes" (Sonic Heroes)
 * "What I'm Made Of" (Sonic Heroes)
 * "Seaside Hill" (Sonic Heroes)
 * "Right There, Ride On" (Sonic Rush)
 * "Jeh Jeh Rocket" (Sonic Rush)
 * "Vela Nova" (Sonic Rush)
 * "A New Venture" (Sonic Rush Adventure)
 * "Blizzard Peaks" (Act 1/Act 2 mix) (Sonic Rush Adventure)
 * "Sky Babylon" (Act 1/Act 2 mix) (Sonic Rush Adventure)
 * "Reach for the Stars" (Sonic Colors)
 * "Aquarium Park" (Act 1) (Sonic Colors)
 * "Starlight Carnival" (Act 1) (Sonic Colors)
 * "Toxic Caves" (Sonic Spinball)
 * "Palmtree Panic" (Sonic CD)
 * "Sonic Boom" (Sonic CD)
 * "Door into Summer" (Knuckles Chaotix)
 * "Diamond Dust" (Sonic 3D Blast)
 * "Super Sonic Racing" (Sonic R)
 * "Sonic Stage" (Emerald Beach) (Sonic Battle)
 * "Neo Green Hill" (Sonic Advance)
 * "Leaf Forest" (Sonic Advance 2)
 * "Route 99" (Sonic Advance 3)
 * "Quick Trip to Paradise" (Sonic Rivals)
 * "Race to Win" (Sonic Rivals 2)
 * "His World" (Sonic the Hedgehog) (2006)
 * "Endless Possibility" (Sonic Unleashed)
 * "High Flying Groove" (Theme of Heroes) (Sonic Riders)
 * "Un-Gravitify" (Sonic Riders: Zero Gravity)
 * "Free" (Sonic Free Riders)
 * "Let the Speed Mend It" (Sonic and the Secret Rings)
 * "Knight of the Wind" (Sonic and the Black Knight)
 * "The Adventure Begins" (Sonic the Hedgehog 4)

Skills
Skills are items both Sonics' can use in acts and some missions. They can be unlocked by doing a certain mission, buying them at the skills shop, or collecting five star rings in an act. Some skills can be used during only one act, and they cost a certian amount of points, to limit the amount of skills Sonic can have at once. Here are the skills they can get, along with their skill point cost:

Classic Sonic

 * Aqua Shield - Enables Bound Jumps and eliminates the need to get air. (70 SP; can be used 1 time per life)
 * Boardmaster - Hop on a skateboard whenever you want. (70 SP; can be used 1 time per life)
 * Breath Holder - Stay underwater longer. (20 SP)
 * Flame Shield - A Shield that enables midair dashes. (70 SP; can be used 1 time per life)
 * Hercules Muscles - Push movable objects faster. (10 SP)
 * Homing Attack - Enables the use of Homing Attacks. (100 SP)
 * Invincible Start - Start the stage with temporary invincibility. (40 SP)
 * Long Spin Dash - Your Spin Dash will carry you further. (30 SP)
 * Power Sneakers - Run faster, plain and simple. (60 SP; can be used 2 times per life)
 * Ring Time - Turns enemies into Rings for a short time. (60 SP; can be used 5 times per life)
 * Shield - A Shield protects you from a single hit. (60 SP; can be used 2 times per life)
 * Thunder Shield - Enables double-jumping. (70 SP; can be used 1 time per life)
 * Treasure Scanner - Allows you to see hidden items and Springs. (40 SP)
 * Twin Spin Attack - Allows you to attack in mid-jump. (30 SP)

Modern Sonic

 * Acceleration - Increases speed when starting to run. (10 SP)
 * Auto-Gauge - Boost Gauge fills automatically over time. (30 SP)
 * Blast Off - Press a button when "GO!" appears for a free Boost. (10 SP)
 * Boost Gauge Up - This extends the length of your Boost Gauge. (60 SP)
 * Direct Jump - Increase the speed of your Wall Jumps. (30 SP)
 * Endless Boost - The Boost Gauge stays full but you can't get Rings. (70 SP)
 * Gauge Rebooter - Begin with a full Boost Gauge upon restart. (30 SP)
 * Power Stomp - Creates a shockwave when Stomp is used. (30 SP)
 * Quick Slide - Enables Quick Step when on a skateboard. (30 SP)
 * Ring Energy Bonus - Collecting Rings fills the gauge faster. (40 SP)
 * Serial Homing - Perform sequential Homing Attacks faster. (40 SP)
 * Smasher Bonus - Breaking enemies, etc. fills Boost Gauge. (30 SP)
 * Speed Up - Increase Sonic's speed. (20 SP)
 * Trick Mastery - Perform Tricks faster. (60 SP)

Both

 * 10-Second Rings - Dropped Rings take 10 seconds to disappear. (30 SP)
 * Athleticism - Lose less speed moving uphill and in water. (20 SP)
 * Infinite Continues - Get infinite continues on the Sega Genesis!
 * Last Chance - Get an extra life when you're out of lives. (50 SP)
 * Life +1 - This gives you one extra life. (Can be purchased as many times as wanted/needed until 99 lives are reached)
 * Power Brake - Stop on a dime no matter how fast you run. (10 SP)
 * Safety Net - Begin with 10 Rings after a restart. (40 SP)
 * Sega Genesis/Mega Drive Controller - Play "Sonic the Hedgehog" on the Sega Genesis/Mega Drive!
 * Super Sonic - Collect 50 Rings to become Super Sonic. (100 SP; can be used indefinitely per life)
 * Sure-Footed - Land on your feet after getting damaged. (20 SP)
 * Time Brake - Slows down time temporarily. (80 SP; can be used indefinitely per life)

Secret Statue Room/Models
In the console/PC version of the game, inside the media room, there lies a secret area where the player can collect many characters with various codes, even characters who didn't appear in the game otherwise.The room is accessible by holding back/select while in the collection room. In the 3DS version's collection room, there's a section called "Models" which is basically the same thing as the statue room. However, the statues are unlocked by doing the missions, rather than using special codes. It should be noted that all of the character and emerald models are from special missions, and the bosses are from boss missions.
 * Sonic the Hedgehog
 * Classic Sonic
 * Miles "Tails" Prower
 * Classic Tails
 * Amy Rose
 * Knuckles the Echidna
 * Cream the Rabbit & Cheese
 * Rouge the Bat
 * Espio the Chameleon
 * Blaze the Cat
 * Vector the Crocodile
 * Charmy Bee
 * Chao
 * Omochao
 * Dr. Eggman
 * Classic Eggman
 * Classic Metal Sonic
 * Shadow the Hedgehog
 * Silver the Hedgehog
 * Big the Cat
 * E-123 Omega
 * Jet the Hawk
 * Hero Chao
 * Dark Chao
 * Chip
 * Moto Bug
 * Buzz Bomber
 * Crabmeat
 * Chopper
 * Grabber
 * Spiny
 * Egg Robo
 * Cop Speeder
 * Spinner
 * G.U.N. Hunter
 * Mono Beetle
 * Egg Pawn
 * Iblis Biter
 * Iblis Taker
 * Iblis Worm
 * Egg Fighter
 * Egg Launcher
 * Egg-Cannon
 * Egg Chaser
 * Sandworm
 * Classic Spring
 * Modern Spring
 * Item Box
 * Capsule
 * Goal Plate
 * Goal Ring
 * Ring
 * Chaos Emeralds
 * Launcher
 * Animal Friends

The models are:
 * Sonic the Hedgehog
 * Dr. Eggman
 * Miles "Tails" Prower
 * Amy Rose
 * Metal Sonic
 * Knuckles the Echidna
 * Big the Cat
 * Shadow the Hedgehog
 * Rouge the Bat
 * Cream the Rabbit & Cheese
 * E-123 Omega
 * Silver the Hedgehog
 * Orbot & Cubot
 * Chaos Emeralds
 * Big Arm
 * Biolizard
 * Egg Emperor
 * Time Eater

Stages
Stages are divided into three eras: the Mega Drive/Genesis era, the Dreamcast era, and the current, Modern era. Levels and Bosses are different between the console and 3DS versions with the exception of Green Hill.

Classic Era

 * Green Hill (Sonic the Hedgehog)
 * Chemical Plant (Sonic the Hedgehog 2)
 * Sky Sanctuary (Sonic the Hedgehog 3 & Knuckles)

Dreamcast Era

 * Speed Highway (Sonic Adventure)
 * City Escape (Sonic Adventure 2)
 * Seaside Hill  (Sonic Heroes)

Modern Era

 * Crisis City (Sonic the Hedgehog (2006))
 * Rooftop Run (Sonic Unleashed)
 * Planet Wisp (Sonic Colors)

Bosses

 * Classic Metal Sonic, Stardust Speedway (Sonic CD)
 * Death Egg Robot, Death Egg (Sonic the Hedgehog 2)
 * Perfect Chaos, Station Square (Sonic Adventure)
 * Shadow the Hedgehog, Final Rush (Sonic Adventure 2)
 * Silver the Hedgehog, Crisis City (Sonic the Hedgehog 2006)
 * Egg Dragoon, Eggmanland (Sonic Unleashed)
 * Time Eater, Center of Time (Sonic Generations)

3DS
Unlike the console versions, after the player beats Green Hill in the first era, they are free to choose which zone and act of the era they want to do first.

Classic Era

 * Green Hill (Sonic 1)
 * Casino Night (Sonic 2)
 * Mushroom Hill (Sonic 3 &amp; Knuckles)

Dreamcast Era

 * Emerald Coast (Sonic Adventure)
 * Radical Highway (Sonic Adventure 2)

DS Era

 * Water Palace (Sonic Rush)
 * Tropical Resort (Sonic Colors)

Bosses

 * Classic Metal Sonic, Casino Night (Sonic 2)
 * Big Arm, Launch Base (Sonic 3 & Knuckles)
 * Shadow the Hedgehog, Radical Highway (Sonic Adventure 2)
 * Biolizard, Cannon's Core (Sonic Adventure 2)
 * Silver the Hedgehog, Tropical Resort (Sonic Colors)
 * Egg Emperor, Final Fortress (Sonic Heroes)
 * Time Eater, Center of Time (Sonic Generations)

Special Stages
Special Stages will appear in the 3DS version. The style of the play is akin to the Special Stages in Sonic Heroes. A Chaos Emerald will be achieved if the stage is completed. Super Sonic will be exclusive to the final boss. It was called "Unlockable Special Stages" during SEGA's press conference regarding the 3DS version of the game. For the console versions, the player collects the Chaos Emeralds by defeating the three bosses and three rivals, plus one more that is automatically given when both Acts are cleared on "Planet Wisp".

Other homages to the series
Sonic the Hedgehog (1991):
 * The underwater sections in Act 1 of Seaside Hill bear features from Labyrinth Zone.
 * The colors from the Console/PC version of Green Hill resemble the ones from the original version.
 * When pressing start in the title screen and when choosing an act in the 3DS version, the weird symbols from the Japanese boxart appear.
 * If the player gets an "A" rank with Classic Sonic, he'll do the pose from the boxart of this game.
 * The Buzzsaws in both acts of Planet Wisp return from Scrap Brain Zone, they were there to increase the Difficulty for the last level.
 * In both acts of Chemical Plant and Water Palace, there are waterslides that function the same way as the ones from Labyrinth Zone
 * In City Escape and Radical Highway certain barrels are set up like the ones from Spring Yard Zone.

Sonic the Hedgehog (8-bit):
 * The colors from the 3DS version of Green Hill resemble the ones from the Game Gear version.

Sonic the Hedgehog 2: 
 * In both acts of Green Hill, there are corkscrew bridges resembling the ones in Emerald Hill Zone.
 * In Classic Rooftop Run, the Gondolas return which came from Hilltop Zone

Sonic CD:
 * Classic Sonic's Crisis City (Act 1) has a 90-degree angle ramp like the "3D" upward ramps in Palmtree Panic.
 * Classic Sonic's City Escape (Act 1) has a similar ramp.
 * In Classic Seaside Hill, there is a secret area along with a red ring, this was here to tribute the secret Angel statue which was found in Wacky Workbench Zone present.
 * In the 3DS version, when Sonic is about to run out of air underwater, the music doesn't change to the drowning theme, like in this game.

Sonic 3 &amp; Knuckles:
 * Act 1 of Seaside Hill and Water Palace contains references to parts of Hydrocity Zone, such as the grabbing poles and the small propellers.
 * In Sky Sanctuary Act 1, there are platforms that fly as Classic Sonic runs on them. They will also wear out and stop working after running on one for too long. These are apparently based off of the spinning blue tops from Marble Garden Zone.
 * The levels having 1 remix per act could be a reference to how the second act of each zone had a slightly remix of the original music.
 * If the player gets a "C" rank with Classic Sonic, he will do the pose from the Japanese boxart of Sonic 3.
 * In Sky Sanctuary Act 2, there are indoor areas that resemble Hidden Palace Zone.
 * If Knuckles is saved by Modern Sonic, he says that it's good to have his sanctuary back, referencing its destruction by Mecha Sonic.
 * The Flying Battery Zone makes an appearance in Rooftop Run.
 * When the player uses "Ring Time" the song is a remix of 3&K's Invincibility song.

Sonic Triple Trouble:
 * The skateboard item Classic Sonic uses in City Escape and the skill "Boardmaster" seems very similar to the board in Robotnik Winter Zone.

Sonic Adventure:
 * The "Finish" pose for Modern Sonic's Combo Tricks is identical to the pose he does on the front cover of the original Dreamcast version of the game.
 * In a mission in which Classic Sonic races Amy in Sky Sanctuary, Amy races by twirling her hammer around in her hands. This seems to reference her Spin Hammer Attack move from this game.
 * Classic Sonic's skateboard has a similar design to the one from one of Sonic's artworks from this game.
 * The Sonics obtain upgrades at some point in the 3DS version, just like how the characters did in this game.
 * Just as an orca chased Sonic in the original Emerald Coast and its 3DS remake, a giant Chopper chased Sonic in the console remake of Green Hill.

Sonic Adventure 2: Sonic Advance:
 * The tube waterslide in Chemical Plant works similarly to the one at the end of Cannon's Core.
 * The cutscene before the fight with Shadow is almost an exact rendition of the opening cutscene from the GameCube version of this game.
 * After defeating the Biolizard, Sonic mentions that it was easy because he has fought it before, referencing the final battle of this game.
 * The first act of Emerald Coast starts in a similar way as the first act of Neo Green Hill.

Sonic Battle:
 * In a mission in which Classic Sonic races Amy in Sky Sanctuary, Amy Races by twirling her hammer around in her hands. This seems to reference one of her attacks from the game.

Sonic Advance 3:


 * In the Amy Co-op Mission in Chemical Plant, she uses her hammer to send up Sonic in the air. This was her partner ability in Advance 3.
 * Sonic is able to call his friends to help him out with their special abilities in some of the missions. He was able to call them in Advance 3 as well.
 * In the final battle (Console/PC version) Sonic is able to throw his partner as a projectile to the Time Eater. This feature comes from the final battle of Sonic Advance 3.
 * The fireworks that Classic Sonic uses at the end of Classic Tropical Resort are similar to the rockets in Toy Kingdom.
 * The way the Sonics bounce on the balloons in Tropical Resort is similar to how Sonic and friends did in Toy Kingdom.
 * The Spinning Tops in Sky Sanctuary Zone are references to the Spinning Tops in Chaos Angel (in terms of design, not functionality).

Sonic Heroes:
 * The giant propellers from the second act of Mushroom Hill are similar to the ones from Frog Forest and Egg Fleet.
 * The giant "Egg Wheels" from Casino Night look similar to the roulette from Casino Park.
 * The special stages are re-imagined versions of the ones from this game.
 * In a mission in which Classic Sonic races Amy in Sky Sanctuary, Amy Races by twirling her hammer around in her hands. This seems to reference her Propeller Hammer move from this game.

Sonic Rush:
 * The combo tricks Modern Sonic can perform are similar to the ones from this game. They also give him boost energy, just like in Rush.
 * Blaze is seeing talking to Cream in Sonic's party, a reference to their friendship from this game.
 * In the 3DS version, when Modern Sonic's boost gauge is completely full, it changes color and lets Sonic boost as much as he wants until it goes back to normal. This is similar to how the Tension Gauge worked in Rush.
 * In the final battle (3DS version), only one Eggman is controlling the Time Eater while facing one of the Sonics. If the Time Eater. gets hit, they go through a portal and switch the Eggman who is controlling it, as well as the Sonic who is facing it. This is a reference to the final battle of this game.
 * In the final battle (Console/PC version) the Sonics combine their powers and start rotating in a circle to deliver the final blow. This is how the final battle of this game ended.
 * The combo finisher Modern Sonic can perform originated from this game. The results are also similar.
 * Each Sonic having a different version of the song for the stage comes from this game in which Sonic and Blaze had a different version of the song when going through the stage.

Sonic Rush Adventure:
 * Blaze mentions that there's something like Red Rings on her dimension too.
 * The dolphins who help Modern Sonic in Emerald Coast are similar to the ones from Pirates' Island.
 * The water cannons from Water Palace Act 1 are similar to the ones from Pirates' Island.
 * The treasure chest from the 3DS version's collection room is the same treasure chest that appeared at the end of every act of this game.

Sonic the Hedgehog (2006):
 * The black holes that appear in the 3DS version's Versus Mode are similar to the ones from End of the World.

Sonic Rivals:
 * The sound effect that plays when Classic Sonic rolls in the 3DS version is the same exact sound from this game.
 * The rivals in the 3DS version are designed in a similar way to the rival races from this game.
 * The three rivals in Sonic Generations were also part of Sonic's rivals from this game.

Sonic Rivals 2:
 * The models of Knuckles, Shadow and Silver in the 3DS version's collection room are based off their artwork from this game.

Super Smash Bros. Brawl:
 * If the player gets a "B" ranking as Classic Sonic, he will pose Sonic's render pose from Brawl.

Sonic Riders: Zero Gravity:


 * The tube waterslide in Chemical Plant works similarly to the one during Aquatic Capital.
 * The texture of Modern Sky Sanctuary (Act 2) strongly resembles Astral Babylon.

Sonic and the Secret Rings:
 * In a cutscene, Modern Sonic mentions "Rescuing genies in magic books."
 * The skill system is similar to the ring system from this game.
 * The Time Break ability in Sonic Generations is very similar to the Time Break in this game, where it originated from.

Sonic Chronicles: The Dark Brotherhood:
 * If the player saves Rouge the Bat in City Escape as Modern Sonic, she will refer to him as "Big Blue" her nickname for Sonic in Chronicles.

Mario & Sonic at the Olympic Winter Games
 * If the player gets a B rank with Modern Sonic, he'll do one of the poses of his artwork from this game.

Sonic Unleashed:
 * The skydiving tunnels in Modern Chemical Plant and the Egg Dragoon boss are a reference to the original Rooftop Run and Eggmanland stages.
 * There is a cylinder-climbing section in Crisis City that works like Mazuri's tree section, in which the player needs to climb the right platforms to get to the exit.
 * In both acts of Rooftop Run, the flags of all the nations Sonic visited in Unleashed are visible at some point.
 * The village in the background of Water Palace looks similar to Apotos.
 * After Modern Sonic gets out of a water slide in Water Palace, he begins to surf, referencing that he was able to do that in the Wii/PS2 version of this game.
 * Modern Sonic obtains the Stomping Shoes at some point in the 3DS version instead of having it from the get-go, just like in this game.
 * Modern Sonic's standard pose in the cutscenes from the 3DS version comes from the artwork of this game.
 * In the final battle (3DS version), the Time Eater throws energy balls at Modern Super Sonic. If they hit him, they will stun him for a few seconds. Perfect Dark Gaia had this power in the Wii/PS2 version.
 * Also in the final battle in the 3DS version, the Sonics boost directly at the Time Eater to deliver the final blow. This is how the final battle of this game ended.
 * In a mission in Seaside Hill, it's set at nighttime, so it looks similar to the Night Stage of Adabat.

Sonic Colors:
 * As well as mentioning genies and magic books, Modern Sonic also mentions "saving aliens in an interstellar amusement park" in the same cutscene.
 * Tropical Resort's references the DS version of the game by including elements of it on its first act.
 * The Face of the Time Eater before being revealed has a similar look to the Frenzy and Void Wisps' appearance, in particular the Void Wisp.
 * Near the end of Modern Rooftop Run, the Battery Blimp attacks in the same way as the Frigate Orcan and Skullian except it can't be destroyed, however it leaves a trail of rings after it takes enough hits.

Sonic Channel:


 * If the player gets an A rank with Modern Sonic, he'll do one of the many poses that he has in the Sonic Channel.
 * Most of the statues in both versions are based off the character artwork from here.
 * In the 3DS version, the "Favorite Character" section on the Profile Card option uses artwork from Sonic Channel.

Reception
Since its release, Sonic Generations has received generally positive reviews, with most reviewers praising the different game styles and feel of nostalgia, but criticizing the over-responsive controls and extra levels with Sonic's friends. IGN gave the game an 8.5 out of 10, praising the overall gameplay and the level design, whilst disliking the few boss battles and the occasionally clunky controls. They also criticized the storyline for being superfluous, although they praised it for paying "homage to Sonic games of the past." Destructoid's Jim Sterling gave it an 8 out of 10, noting that "If Sonic Team can keep this up, then the blue blur will most definitely be back on top." Computer and Video Games gave it a 7.5/10, commenting that "the balance of intensity and fairness is just about spot on" from a design perspective, but arguing that the game occasionally moved too fast for the player to respond well to obstacles and that "the framerate dips dramatically" in the 2D sections, which can be jarring. The review added that "it's a shock how much easier on the eyes" the original Sonic the Hedgehog is, "with its thumping great pixels and velvety-smooth parallax scrolling," and that the 3D sections run much smoother because "there's so much action going on in every direction that jerkiness on a single plane is far less noticeable." Finally, the review criticized the addition of characters like Amy, Knuckles, and Cream for side missions while praising "the level of effort and creativity" that went into the "immense" levels. 1UP gave the game a B score, writing that "Generations' liberal borrowing from Nintendo's school of game design stands as one of Sega's smartest decisions in years," its "challenges feature an amazing amount of variation" and concluding that it "has quite an array of impressive and fun-to-play levels, full of interesting set pieces that draw from Sonic’s past." Their only complaints were that many levels featured on-rails or auto-pilot sequences "which can be frustrating and often jarring when control is suddenly thrust back into your hands" and that the warning signs which prepare the player for pitfalls are "easy to miss." PlayStation Official Magazine gave it an 8/10, stating that "each act is a masterpiece of platform game design... it's sprawling and focused all at once, every pixel placed with the express purpose of making you go really, really fast" and noting that the difficulty was so perfectly balanced that "no matter how many times I missed a jump or drowned Sonic (I remain convinced that hedgehogs can swim), I blamed my slow thumbs rather than the game." However, the review felt that "the more stationary challenges – digging for medals with Knuckles, for example – are tedious." Nintendo Power gave the 3DS version of Sonic Generations a 8.0, saying that it should please any Sonic fan but criticized that the game can be finished in an afternoon. IGN gave it a 7.0, saying that while the game is good and pretty enjoyable, it is not the best handheld Sonic game. Unlike Sonic Colors, the game did not get many awards in the first year having only one of Gamezone's Best Presentation award. It's lowest rating was given by EDGE giving it 5/10. On the 2011 Nintendo Power Awards, the 3DS version of Sonic Generations won the "Best Retro Revival" award.

Gallery

 * For more: Sonic Generations/Gallery.

Merchandise
The game had two newly revealed action figures at Comic-Con 2011. Now early on Nintendo has released these official new Sonic Generations shirts to remark the 20th birthday for a kicking price of each.

Jazwares has also released a line of Generations themed toys, from a character with an iconic badnik with a picture of a stage to giant stuffed animals. They call it 20th anniversary figures

Adaptations
Archie Comics produced a video game tie-in for Sonic Generations in Sonic The Hedgehog Issue 230.

A short manga for Sonic Generations was released in Japan. It has been presented in a similar format as to the Sonic Unleashed manga and Sonic Colors manga.

Trivia

 * For the first time, the PS3 version of the game is locked at 30fps, while previous PS3 Sonic games would run at 60fps max. This makes the two current console versions very similar outside of the controller. The later PC port has an edge over the console versions and runs at 60fps, though the unlockable version of Sonic the Hedgehog has been removed (probably because it is an obvious emulation and has already been ported to PC in numerous formats). Incidentally, the level select code for that game was made inaccessible in the Xbox 360 version.
 * This is the first Sonic game to have stereoscopic 3D capability.
 * The 3DS version is the first handheld game on a Nintendo console that features fully rendered 3D stages and dynamic camera angles.
 * Knuckles, Rouge, Espio, Blaze and Charmy are the only characters that are saved and appear in a stage of that game, with Knuckles in Sky Sanctuary (S3&K/S&K), Rouge in City Escape (Sonic Adventure 2), Espio in Seaside Hill (Sonic Heroes), Blaze in Crisis City (Sonic the Hedgehog 2006) and Charmy in Planet Wisp (Sonic Colors DS).
 * Tails is the only character who races against Modern Sonic. Knuckles and Amy race against Classic Sonic.
 * When racing against Tails and Knuckles, a remix of Super Sonic Racing from Sonic R plays. When racing against Amy though, a remix of Emerald Beach from Sonic Battle plays.
 * Interestingly, within the remix of Super Sonic Racing, are segments from commercials for the Sega Saturn.
 * Jun Senoue mixed the tracks for this game. The music also speeds up and slightly changes when Modern Sonic uses his boost, but only in Green Hill and Sky Sanctuary.
 * This is the first 3D Sonic game not to have a theme song.
 * As such, this is the third 3D Sonic game not to use the main theme song (or even a remix) for the final boss. The other two being Sonic Heroes and Sonic and the Black Knight.
 * The Classic version of City Escape's theme has a clip of the Endless Mine theme from the multiplayer mode of Sonic the Hedgehog 3.
 * If noticed, Classic Tails's artwork seems to have "buckles" under his gloves (above his shoes).
 * Like Sonic Unleashed (Wii/PS2), when using the Sonic Boost while on a Dash Panel, Sonic uses a Spin Attack.
 * The Blast Off skill in the console/PC versions is similar to the free boost-giving move available in the Wii/PS2 versions of Unleashed.
 * The E3 demo, Sonic Boom, is named after the opening theme in the US version of Sonic CD. Crush 40 and Cash Cash performed a remix of this song at Sonic Boom. The original song can also be unlocked in the game and be heard on any stage if the player chooses to change the music for any of the stages.
 * In City Escape, Fang the Sniper, Bean the Dynamite, Bark the Polarbear can be seen in "wanted" posters, while Mighty the Armadillo and Ray the Flying Squirrel can be seen on a "missing" poster.
 * Like the street signs in Empire City from Sonic Unleashed, City Escape has various buildings named after characters, such as Tails' Pizza, Coffee Blaze, Amy's Market and Vector's Daily.
 * Near the end of Act 2 in Green Hill in the home console version, Modern Sonic is being chased by a giant Chopper, clearly a reference to when he was chased by a orca in both Sonic Adventure and Sonic The Hedgehog (2006).
 * When doing a finish to one of his mid-air Combo Tricks after going through a rainbow-colored hoop or a special dash panel ramp, Modern Sonic does the same widely recognizable pose as he does on the cover for Sonic Adventure.
 * The first 2 gameplay trailers featured an instrumental version of famous songs:
 * Tenderoni by Kele Okereke (Green Hill).
 * Na Na Na by My Chemical Romance (City Escape).
 * This is the first time Modern Sonic gets Boost Energy from both Rings and Enemy Power in a handheld console.
 * A deleted CGI scene shows Modern and Classic Sonic running through Rooftop Run, destroying Egg Fighters, boosting and Spin Attacking then meeting up with the two Tails at the end near the Spagonian clock tower. Some of these parts could be seen in the "Two Sonics" trailer but the full video was not put in the game.
 * In this game, Classic Sonic has various waiting animations from the classic games. One is when he looks at his 'watch', from Sonic 2, one is when he points foward (or behind him if he's backward) to the right, from Sonic 3 and one is when he crosses his arms and taps his foot two times quickly, from Sonic 3D Blast. These are not present in the 3DS version, however. Classic Sonic will only show the waiting animation, and after a while fall asleep.
 * This game has been in development since Sonic Unleashed was released.
 * If noticed, the console/PC versions have a white colored design on top and bottom, where as the 3DS version has a replacement for blue, this is reference to the consoles and handheld's version's Japanese name, White Time and Space (console/PC) and Blue Adventures (3DS).
 * If noticed, when watching movies in the Collection Room, Sonic sits down and watches a TV screen, as if he's watching the movie with the player.
 * This is the first main series Sonic game on the PS3 and 360 to have hidden trophies/achievements.
 * In the Xbox 360 version of the game, the Statue Room can be accessed by entering the Collection Room and holding down the "Back" button, and the select button in the PS3 version. The PC version also has an equivalent mapped to the "Back" button.
 * In this game, Sonic, Tails, Dr. Eggman and Metal Sonic are the only characters with a Classic and Modern form of themselves, but Metal Sonic is only seen in his classic form.
 * The rivals appeared as playable characters in Sonic Rivals.
 * Knuckles is the only rival from Sonic Rivals that is a friend in Sonic Generations as the others are all bosses.
 * In the Console/PC version, the countdown to drowning starts at 4 instead of 5 although a different tone is played before the countdown starts.
 * In the 3DS version however, the countdown starts from the traditional 5.
 * On the case cover of the console/PC version, Modern Sonic's run looks similar to the one on the case cover of Sonic the Hedgehog (2006) which was also released on the 360 and PS3 consoles. On the 3DS one, Modern Sonic looks similar to the one on the case of Sonic Classic Collection, which was released on the DS.
 * Neither of Speed Highway's acts include the At Dawn Section from Sonic Adventure. 
 * Crisis City appears in this game, despite the ending to Sonic 2006 erasing the timeline. Blaze also comments on how she thought she'd never see Crisis City again. This has led to questioning as to how she remembers the location.
 * The Dreamcast Era is the only era in which Dr. Eggman is not a boss.
 * In the E3 demo of Green Hill Act 2 (when the game was in early development), at the beginning of the stage, Sonic said "Ready?...Go!", while in the final game, he doesn't.
 * If a 10 Rings box is destroyed in the Console/PC version, the sound when you got a Ring sounds ten times instead of one. In the 3DS version however, it only sounds once.
 * Although no levels from Sonic & the Secret Rings are returning, Sonic makes reference to the events of the game during the second cutscene when he reunites with Tails. "No stranger than rescuing genies from magic books,"
 * In a cutscene that plays after Modern Sonic finishes Chemical Plant, Tails makes an obvious joke about drowning in Sonic 2's Chemical Plant Act 2.
 * This game directly follows the events of Sonic Colors, according to Dr. Eggman's plan in this game.
 * After Sonic saves Tails, he makes a reference, saying that the stage was "awfully familiar", followed by Tails saying that he doesn't recognize the stage at all. Most likely referencing the fact that Green Hill Zone is a Sonic 1 stage, and Tails was introduced in Sonic 2. Yet in Sonic Chronicles: The Dark Brotherhood, Tails recognizes Green Hill Zone.
 * This is the second 3D Sonic game where Eggman is the final boss.
 * A floating pot-like enemy named Sprinkler from Sonic Colors returns in a mission to Planet Wisp, as well as a number of other levels.
 * Out of all 9 main stages, 3 of the stages are based on the first levels of their respective games (Green Hill, City Escape and Seaside Hill). The 3DS Version has Green Hill, Emerald Coast and Tropical Resort (Mushroom Hill is technically a first stage as well though not in the complete Sonic 3 & Knuckles). To a lesser extent, Crisis City is also considered a starting level (but in the case of Silver, and not Sonic). It can also be said that Radical Highway is a first level of sorts due to being Shadow's first level in Sonic Adventure 2.
 * There are also plays on numbers. Chemical Plant is the second level of the Classic Era (which itself is the second level from Sonic the Hedgehog 2, the second game of the series) and is the second level of the game overall. It can also be noted that while Amy never appeared in Sonic 2, she was the second friend Sonic made in the main series. Crisis City, Rooftop Run, and Planet Wisp (depends on the player's choice in Colors, but it does follow Challenge Mode in the Wii version) are all the fourth stages of their respective games (and coincidentally, all are in the Modern Era).
 * This is the second main 3D game to have someone (Classic Tails, specifically) call Dr. Eggman the name "Dr. Robotnik", the first being Sonic Adventure.
 * Ironically enough, Eggman referred to himself as Dr. Robotnik in Sonic Adventure, but Classic Eggman stated that "Nobody calls him that anymore".
 * Chemical Plant is the only main stage not shown in the Launch Trailer.
 * If noticed, Classic Metal Sonic's pose is similar to Shadow's.
 * In various points of Crisis City, a destroyed ad for "Chao in Space III" can be seen.
 * In various points of Radical Highway, signs that say "Time Eater" can be seen.
 * Sonic Generations is the sixth Sonic game to use Time Travel as a theme. The five others are Sonic CD, Sonic Adventure, Sonic the Hedgehog (2006), Sonic Rivals, and Sonic Rivals 2.
 * In the cutscene after the final boss, Classic Sonic attempts to use a Sonic Boost but fails.
 * He manages to do it in the 3DS version, though it wasn't as good as Modern Sonic's, as he pointed out that "he was gonna keep getting better".
 * In both versions of the game, Classic Sonic has the ability to perform the Homing Attack. In the console versions, it is a skill purchased in the Skill Shop (obtained by collecting all Red Star Rings in Planet Wisp, Act 1, and it uses all skill points). In the 3DS version, it is learned just before the Dreamcast era.
 * This is the second 3D Sonic Game where players start a new game and taken to the first stage, rather than showing the cutscene first. The first being Sonic Colors.
 * Despite the fact that they never appear in the game itself (with the exception of cameos) Jet the Hawk, E-123 Omega, Chip, and Big the Cat all have trophies in the secret trophy room. Orbot and Cubot also appear as trophies in the 3DS version.
 * If noticed, Classic Tails randomly appears after the boss battle with the Death Egg Robot/Big Arm. Takashi Iizuka said that their was going to be an explanation but it never got worked into the game's story, and he wanted to leave it open to the fan's opinion.
 * "History of the 1st Stage: White Edition" and "History of the 1st Stage: Blue Edition" are the Japanese Pre-order bonuses for the HD and 3DS versions respectively, not the soundtrack as originally thought. They are both disks with separate soundtracks that consist of music from the first stage of the franchise.
 * The only main series past games that are not referenced are Shadow the Hedgehog and Sonic the Hedgehog 4, however Super Sonic's theme is the Invincibility song from Sonic 4 and one of the song's played when fighting Shadow is "All Hail Shadow" from Shadow the Hedgehog. Both games also feature an unlockable song in any version of the game. (Splash Hill Zone - Act 1 from Sonic 4, and I Am... All Of Me from Shadow the Hedgehog)
 * Takashi Iizuka said that three original taglines for the game were "Blast with the past," "Déjà Blue," and "A speedy trip down memory lane."
 * While the console/PC version considers Sonic Heroes as part of the Dreamcast Era, the 3DS version considers it part of the Modern Era.
 * In both versions, the bosses of the eras are all final bosses of a story. The only exceptions are the Biolizard, which had the Finalhazard come after it in Sonic Adventure 2 (although it could be considered a second phase of the same boss), and the Egg Dragoon, which had Perfect Dark Gaia come after it in Sonic Unleashed.
 * With the exception of Egg Dragoon, all of the bosses in the console/PC version can only take half the amount of hits the 3DS version's bosses can. (4 in the console/PC version, 8 in the 3DS version).
 * The difficulty has increased or decreased depending on the placement of the level when compared to the original level. For example, Rooftop Run has less boosting and more platforming than the original version. It can also be said that Planet Wisp is just as hard as the original version (which may be the reason it was included). Tropical Resort was also made harder, with new obstacles such as laser gates, Fire totem heads and falling meteorites.
 * While the console/PC version uses the shields (Standard, Flame, Thunder, and Bubble) as skills, the 3DS version has them hidden through the levels, resembling the original games. However, only the Standard and Thunder shields appear in the 3DS version (like in previous handheld titles, both shields for Classic and the standard one in the Modern Era for Modern Sonic) while in the console/PC version all of the shields appear, but only for Classic Sonic.
 * In the 3DS version however, the shields can also be obtained as extra skills by playing in Versus Mode online.
 * When playing the original Sonic the Hedgehog on the Sega Genesis, a top score and top time can be recorded. However, the player must finish the game to save said data.
 * In the console and PC versions, when Classic Sonic gets an invincibility, the music that plays is always the classic remix. However in the 3DS version, the remix that plays depends on the era where Classic got the invincibility (Classic remix in the Classic Era, Modern remix in the Dreamcast and Modern Eras).
 * In the Nintendo 3DS version, Modern Sonic can also find invincibility item boxes scattered around in the Modern Era. The modern remix is played.
 * Strangely enough, the modern invincibility remix is unused in the Console/PC versions, as those versions lack powerups for Modern Sonic at all.
 * In the Console and PC versions, the Classic Era is the only era without a city level while in the 3DS version the Modern Era is the one without a city level.
 * The Console/PC version of the game had the highway stage of Sonic Adventure, and the first stage of Sonic Adventure 2. The 3DS version is the opposite; it has the first stage of Sonic Adventure, and the highway stage of Sonic Adventure 2.
 * In the Console/PC versions of this game, if you stand next to the levels in the hub world, you'll hear a remix of the song in the level. Usually it is an Orchestral remix, using a cello or trombone as the melody, but sometimes it can be Rock music (Like Speed Highway) the music played when next to the Egg Dragoon is a remix of "E.G.G.M.A.N" erasing the lyrics, and when next to the Time Eater boss, no music is played. When next to Shadow, a remix of Shadow's SA2 theme is played, and when next to Silver, a remix of "Dreams of Absolution" is played.
 * Although a stage in the 3DS version, Sonic never went to Radical Highway. Instead, Shadow did.
 * In the Hub World, Sky Sanctuary has trees with grapes in them. In the manual of Sonic & Knuckles it's mentioned that Knuckles's favorite food is grapes, and Sky Sanctuary is also where Knuckles is saved in Sonic Generations.
 * There are unused clips of Modern Sonic and Classic Sonic dancing.
 * When an S rank is achieved on one of the levels or bosses in the Console/PC version, the text color of the title of it turns Golden.
 * When an A rank is achieved from a level in the Console/PC version, the title turns green.
 * In the Console/PC version, the unlockable music list has slight remixes of the Classic Sonic songs (Mainly Sonic the Hedgehog 3 and Sonic & Knuckles).
 * After a stage is restored in the Console/PC version, on the levels background noises can be heard, faint from the background music. This is easily heard when muting the music:
 * Green Hill, sounds of the waterfalls and birdsong are heard
 * Chemical Plant, sounds of construction are heard
 * Sky Sanctuary, loud birdsong is heard
 * Speed Highway, moving, honking cars are heard.
 * City Escape, crowds talking are heard
 * Seaside Hill, sounds of a beach are heard
 * Crisis City, sounds of volcanic explosions are heard
 * Rooftop Run, faint crowds are heard.
 * Planet Wisp, a mix of birdsong and construction is heard.
 * Even though Sonic restored color to Crisis City, he didn't really restore life to the city, as it's still dead/destroyed and barren of people.
 * Although Super Sonic is freely playable after beating the Console/PC version, he has been altered since the Mega Drive games. He accelerates faster and still hovers just above the ground instead of running, but his top speed (Classic's is arguable to be actually slower than in normal form) and jumping height remain unchanged. The rings necessary to hold the transformation also deplete faster than before (roughly 2 per second for both Sonics, and when Boosting under most circumstances as Modern it drains Rings at a very fast pace), probably because unlocking him requires significantly less effort than in past titles. However, he still looses only 1 ring per second during the final boss.
 * In the console/PC version, the Death Egg Robot is the only boss originally fought by Sonic as himself, Perfect Chaos was fought by Super Sonic and the Egg Dragoon was fought by the Werehog.
 * Classic Sonic in his super form retains his black eyes (like in Sonic 2) instead of changing to the blue green eyes from Sonic 3 and Knuckles. Coupled with his lack of the jump attack from Sonic 3 and the fact that only Classic Tails is also shown, it is possible that Classic Sonic comes from the time between Sonic 2 and Sonic 3. However Classic Sonic's appearance resembles Sonic 1 and Sonic CD rather than Sonic 2. Also, Classic Sonic learns the Homing Attack which is used later in Sonic the Hedgehog 4.
 * In the Console/PC storyline, the Time Eater appears when Sonic's Party is happening. In the 3DS storyline, the Time Eater appears before the party happens.
 * On the Console/PC version, Classic Sonic and Modern Sonic fight each rival (Classic Metal Sonic, Shadow the Hedgehog, minus Silver the Hedgehog) in the areas he fought them in the original games, but the 3DS version has Sonic fight them in areas he didn't fight them in the original.
 * In the 3DS version, Big Arm is arguably the only boss Sonic truly fought himself (Sonic fought the Biolizard along with Shadow on it's final form, and he fought Egg Emperor with Tails and Knuckles).
 * This is the second game to use skill customization, the first being Sonic and the Secret Rings.
 * In the credits on the console versions, Sky Sanctuary is credited from Sonic & Knuckles, rather than Sonic 3 & Knuckles. In the 3DS version, Radical Highway is the only stage that has screenshots not depicting Sonic (obviously, as Shadow was originally playable), and Tropical Resort is the only stage that has screenshots from two different versions of the same game (Wii and DS).
 * The launch trailer for the 3DS version has a small mistake. During the Modern gameplay showcase, a clip from Classic Water Palace is shown.
 * The 3DS version is to date only the third game to feature monitors (instead of capsules or nothing) in Modern Sonic's stages. The first game was Sonic Pocket Adventure, which while it technically uses classic gameplay, the design for Sonic is modern.
 * Both City Escape and Radical Highway are the first stages for both Sonic and Shadow in Sonic Adventure 2 respectively.
 * In the console and PC versions, it takes about 5 seconds for Classic Sonic to get impatient and 35 to lay on the ground. However, in the 3DS version, it takes 30 seconds for him to get impatient and a whole minute to lay down.
 * In the console version, Egg Flappers are not present in Seaside Hill. Instead, Spinners replaced them, but they did not appear in Sonic Heroes. However, the Egg Flappers and their aquatic variation do appear in the 3DS version in Water Palace.
 * This is the first Modern Sonic game on a Handheld Nintendo system not to have after-images of Modern Sonic while he's running.
 * This is the only anniversary title that didn't introduce another hedgehog character to the series. Shadow was introduced in Sonic Adventure 2 and Silver was introduced in Sonic the Hedgehog (2006).
 * Not all of the original Animal Friends were present in the game, the ones missing were Ricky, Pocky, and Rocky.
 * This the first time Mushroom Hill, Emerald Coast and Radical Highway have appeared on a handheld.
 * This is the first time the Bomb item has appeared since Sonic Riders: Zero Gravity.
 * Since the ranking system in this game is mostly focused on the time it took to complete an act instead of rings, score along with time like previous games, it gives you a high score and ranking even if you have no rings. This means that the time it takes the player to clear a stage or a mission is more important in the game and could be considered a connection to the time traveling of this game.
 * In the Console/PC version, Omochao works as a guide by giving advices to the Sonics while in the 3DS version, Tails is the one giving advice (Classic Tails to Classic Sonic and Modern Tails to Modern Sonic).
 * In the 3DS version, Classic Sonic's model becomes shinier when the player turns on the 3D effect.
 * Counting both versions, Sonic Generations contains 15 stages and it represents 10 games (11 counting the DS version of Sonic Colors).
 * Every era in both versions (Exept for Modern Era in Console/PC version) contains a first level of a Sonic game.
 * Killer whales appeared in both versions of the game, in Seaside Hill (360/PS3/PC) and Emerald Coast (3DS).
 * The sixth zone of both versions is a water-themed one.
 * This is the first anniversary game to be on a handheld that isn't a port.
 * In the handheld version, each rival is faced in the second level in each era.
 * Coincidentally, each rival appeared in a level of another game they appear in.
 * In the 3DS version, if Sonic gets a standard shield while having a Thunder one equipped, he will keep the Thunder shield instead of switching to the standard one.
 * Although Amy did not appear in Sonic 2 she did make her first appearance in Sonic CD, a game that was developed during Sonic 2 and released shortly after. Metal Sonic can also be found near the Chemical Plant stage.
 * In the Console/PC version of the game, Silver and Shadow do not appear at Sonic's birthday party at the beginning of the game, but show up for the party at the end of the game.
 * All the rivals are hedgehogs or robotic copies of hedgehogs.
 * Amy is the only hedgehog to not fight Sonic in the Console version of the game.
 * Some artwork from Sonic Colors (DS) are the same from Sonic Generations, such as a concept art for Planet Wisp