Sonic Generations

"Hey Sonic! Enjoy your future! It's gonna be great!"

- Modern Sonic

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. 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. All versions of this game can be played in 3D, but a 3DTV as well as a pair of 3D glasses are required for the PlayStation 3 and Xbox 360. It uses stereoscopic 3D with the involvement of a pair of screens in one.

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 2D/3D gameplay of recent titles such as Sonic Unleashed and Sonic Colors, featuring the Homing Attack, Combo Tricks, a Drift, the Stomp, the Light Speed Dash, and the Sonic Boost. Red Star Rings return in the console version. Five can be found in each Act, and collecting them unlocks extras such as music, art, and movies.

The hub world starts out at 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 Challenge Acts 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 version, 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. Act 1 is played as Classic Sonic and Act 2 is played as Modern Sonic, and there are 10 missions per level.

Classic
Classic Sonic stages consist of him running in a permanent two-dimensional perspective, platforming all the way towards an end sign post just like in the original games in the 1990s. Patrick Riley referred to Classic Sonic levels as "momentum-based platforming".

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

Modern Sonic


The levels follow the 2D/3D style gameplay of Sonic Unleashed and Sonic Colors, featuring techniques such as boosting and homing attacks. As well as classic power-ups such as Invincibility and Speed Shoes, certain levels have unique power-ups, such as skateboards in City Escape and Wisp powers in Planet Wisp.

The player can perform Combo Tricks, which can be used to fill up the boost gauge, by launching off Trick Ramps or passing through Rainbow Rings. There is a new visual element to all returning levels, such as the cave in Green Hill. There is more platforming involved, the camera is immovable and quick reaction times are necessary.

Extra
The Skill Shop, owned by Omochao allows players to use points earned from high scores to unlock upgrades such as abilities, shields, and even the original Sonic the Hedgehog Genesis game. Completing challenges, as well as finding Red Star Rings hidden in each of the main Acts, unlocks additional skills, as well as bonus concept artwork and music. The music can then be played in any stage, challenge, or boss fight. There are also online leader-boards for two modes: Ranking Attack, which challenges players to obtain the best time and score on each level, and 30 Second Trial, which challenges players to see how far they can get through a level in 30 seconds.

Handheld
In the handheld version, Modern Sonic's gameplay is similar to that of Sonic Rush and Sonic Colors (DS version). He has the Sonic Boost, the ability to slide under obstacles, jump off walls, and 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 console version, Modern Sonic is only able to wall jump off certain panels (similar to the DS version of Sonic Colors), but in the handheld version, he is able to wall jump on any wall (much like Sonic Unleashed and the Wii version of Sonic Colors).

Development
Development of Sonic Generations began in 2009 when Takashi Iizuka realized that there was no anniversary game planned for 2011. His idea for a tribute was accepted by Sega and development began. An internal poll was held by Sega for employees of Sega, including Sega of Japan, America and Europe asking what their favorite levels from the Sonic series were. After ranking the most popular levels, a website was launched holding another poll asking the opinions of fans of the series.

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 in 2D and 3D. The game was alleged to be released on all major game consoles at the time: PSP, PS3, Xbox 360, Wii, and DS.

On 18 April 2011, Sonic Generations was finally announced for the PS3 and Xbox 360. A GameStop release list printed on 7 May 2011 showed a 3DS port of Generations with a tentative release date of 31 December 2011. 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 2011 issue of Nintendo Power finally confirmed a 3DS version of Sonic Generations. It contained an in-depth preview and interview with Takashi Iizuka.

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.

Sega officially announced a PC version of the game on 11 October 2011. This version was outsourced and developed by UK company "Devil's Details".

Console/PC
The game's plot takes place following the events of Sonic Colors, in which Sonic the Hedgehog defeats Dr. Eggman and sends him out into space. In the past of Green Hill, Classic Sonic is running until he hears a noise. Suddenly, the Time Eater appears in the sky and the screen washes white.

In the present day, Sonic celebrates his birthday with his friends until a mysterious entity known as the Time Eater disrupts the party, sucking everyone through various "time holes" and scattering them across different points in Sonic's past. Sonic tries to stop the monster, but is easily overwhelmed by its power. After regaining consciousness, Sonic finds himself in a strange dimension known as White Space, a realm where time and space end up after they have been 'erased' by being drained of color and life. Sonic rescues his best friend Miles "Tails" Prower, and as they search for their friends, they encounter versions of themselves from the past, referred to as their "Classic" selves. As the two Tails determine that Time Eater's actions are damaging time and space itself, which is why it is white and lifeless, both Classic and "Modern" Sonic race through their history, restoring time to normal and rescuing their friends. The also realize at one point that the Time Eater's weakness are the Chaos Emeralds.

After restoring the worlds and collecting all the Chaos Emeralds, they discover that the mastermind behind the Time Eater is Eggman and his classic self, who was faking himself to be a victim of the Time Eater all along. He reveals that while drifting through space following the events of Sonic Colors, Eggman discovered the Time Eater, getting the idea to use it's powers and decided to join forces with his past self to harness its power. Although the Time Eater manages to nearly defeat the two Sonics, the support of their friends and the power of the Chaos Emeralds allow them to transform into Super Sonic and confront both versions of Eggman. Despite attacking with missiles, warping arms and slowing down time, the Sonics penetrate the Time Eater's core, destroying it. The heroes return to the present and continue celebrating Sonic's birthday. After the party, Classic Sonic and Classic Tails travel back to their own time as everyone bids their farewells.

A post-credits scene shows the two Eggmen lost in 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 Tailses 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 is closing, so he and Classic Sonic have 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.

In the post-credits scene, both Classic and Modern Eggman are trapped in the White Space, and argue with each other. The real difference is that a teaching degree is not mentioned, and it simply ends with Classic Eggman asking his future self what time it is a second time.

Reception
Sonic Generations was very well received by critics. Much praise was given to the gameplay, level design, speed and graphics whilst criticizing the story and overall length of the game. Playstation Official Magazine stated that "Sonic Generations was a masterpiece of platform game design" and Gametrailers said that "Sonic Generations is the best Sonic game this decade". As of 31 January 2013, Sonic Generations has sold approximately 2.4 million copiesand is still selling.

However, the 3DS version received much less praise than its console counterpart, with critics complaining about the similarities between Classic Sonic & Modern Sonic, the lack of handheld levels and the overall replay value, but was praised for keeping the stage's designs extremely faithful to their original design.

Sonic Boom
A Sonic Generations demo was playable at 2011&apos;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 8, 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!" was heard 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 23. 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 12, 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 18 and was released in North America for PSN on October 25. The demo contains both classic and modern Sonic playable in Green Hill Zone, and has no time limit.

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 Red Star Rings in an act. Some skills can be used during only one act, and they cost a certain amount of points, to limit the amount of skills Sonic can have at once.

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. The card patterns were taken from different Sonic games, including all the ones that are represented in Generations. There are patterns of games such as Sonic 3D, Sonic the Hedgehog 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 two ranks, the card changes to a new color. For example, when a card is Rank Beginner (second 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 sparkles.

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 leader-boards 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's "Play Coins" (earned by using the pedometer) to buy content such as new missions (which usually cost five Play Coins each) in case one is unable to StreetPass. The player can also unlock extra content by playing online. With StreetPass, the player can exchange their profile card 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. After time runs out, a sign post is placed in the spot where the player is standing. They have the option to try again or continue playing to find the sign posts of their friends who are ahead or hopefully behind them. They can upload their score online and see which of their friends made it the farthest in one specific level.

Time Attack
In this mode, the player can see how fast he/she can clear a stage, a rival, or a boss fight, and can share their time in online leader-boards. 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 leader-boards. In the console version, Time Attack can only be done online, and only the eighteen main Acts can be played for a top time.

Playable

 * Sonic the Hedgehog (Both Classic and Modern)
 * Super Sonic (Both Classic and Modern)
 * Miles "Tails" Prower (Classic; in "Tails: Toxic Skies" mission)

Allies

 * 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 and a City escape 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-102 Gamma - Profile Card (3DS only, optional favorite character)
 * 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.
 * Mephilies the Dark-Crisis City
 * Dark Gaia

Enemies

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

Console/PC

 * Moto Bug - Green Hill
 * Giant Moto Bug - Green Hill (mission)
 * Chopper - Green Hill/Seaside Hill
 * Mega 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 (H) - Rooftop Run
 * Egg Launcher (H+V) - Rooftop Run
 * Egg Launcher (V) - Rooftop Run
 * Egg Chaser - Rooftop Run
 * Aero-Cannon - Rooftop Run
 * Sandworm - Planet Wisp
 * Buzzer - Planet Wisp

Nintendo 3DS

 * Moto Bug - 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 Bosses

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

Nintendo 3DS Bosses

 * 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)
 * Flame Shield
 * Lightning Shield
 * Aqua Shield
 * 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.

Unlockable Music
Music can be unlocked by completing some missions or collecting a number of Red Star Rings. The player can view his/her unlocked music by going to the collection room. The music for each stage in the game can be replaced by any unlocked music. There is a total of 50 unlockable songs for each version.

Console version

 * "Green Hill Zone (Original)" (Sonic the Hedgehog (1991))
 * "Marble Zone" (Sonic the Hedgehog (1991))
 * "Star Light Zone" (Sonic the Hedgehog (1991))
 * "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 & Knuckles)
 * "Flying Battery Zone" (Sonic & Knuckles)
 * "Death Egg Zone" (Sonic & 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 Stages" (Sonic Heroes)
 * "Sonic Heroes" (Sonic Heroes)
 * "What I'm Made Of..." (Sonic Heroes)
 * "His World" (Sonic the Hedgehog (2006))
 * "Wave Ocean" (Sonic the Hedgehog (2006))
 * "Kingdom Valley" (Sonic the Hedgehog (2006))
 * "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 the Hedgehog Spinball)
 * "Palmtree Panic Present (JPN)" (Sonic CD)
 * "Sonic Boom" (Sonic CD)
 * "Stardust Speedway Bad Future (US)" (Sonic CD)
 * "Diamond Dust Zone" (Sonic 3D)
 * "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 Hedgehog)
 * "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: Episode I)

Handheld version

 * "Green Hill Zone" (Sonic the Hedgehog (1991))
 * "Marble Zone" (Sonic the Hedgehog (1991))
 * "Star Light Zone" (Sonic the Hedgehog (1991))
 * "Emerald Hill Zone" (Sonic the Hedgehog 2)
 * "Chemical Plant Zone (Original)" (Sonic the Hedgehog 2)
 * "Special Stage (Bonus Challenge)" (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 & Knuckles)
 * "Flying Battery Zone" (Sonic & Knuckles)
 * "Death Egg Zone" (Sonic & 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 the Hedgehog Spinball)
 * "Palmtree Panic" (Sonic CD)
 * "Sonic Boom" (Sonic CD)
 * "Door into Summer" (Knuckles' Chaotix)
 * "Diamond Dust" (Sonic 3D)
 * "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: Episode I)

Statues/Models
Inside the media room of the console/PC version of the game, there lies a Statue Room where the player can collect many characters with various codes, even the regular enemies and four characters who didn't appear in the game otherwise. The room is accessible by holding Back (Xbox 360 and PC)/Select (PS3) while in the collection room. These statues are:
 * 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

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.

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 Modern era. Levels and bosses differ 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)

Modern Era

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

Bosses

 * Classic Metal Sonic, Casino Night (Sonic the Hedgehog 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 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 symbols from the Japanese boxart appear.
 * If the player gets an "A" rank with Classic Sonic, he'll do the pose from the box art of this game.
 * The Buzzsaws in both acts of Planet Wisp return from Scrap Brain Zone.
 * 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 8-bit 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 Hill Top Zone.
 * In both acts of Chemical Plant and Water Palace, there are waterslides that function the same way as the oil slides from Oil Ocean Zone (although they first appeared in Labyrinth Zone).
 * When left waiting long enough without getting talked to in front of Green Hill Zone Modern and Classic Tails yawn like they first did in this game.

Sonic CD:
 * Classic Sonic's Crisis City (Act 1) has a 90-degree angle ramp like the "3D" upward ramps in Palmtree Panic present.
 * 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 past.
 * 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 the Hedgehog 3 &amp; Knuckles:
 * Act 1 of Seaside Hill and Water Palace contain 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 on the spinning blue tops from Marble Garden Zone.
 * If the player gets a "C" rank with Classic Sonic, he will do the pose from the Japanese box art of Sonic the Hedgehog 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 collapse.
 * On certain challenges, Classic Sonic has to "juggle" the Goal Post to a certain area in the stage. This could be a reference to the functions of the Goal Post in Sonic 3 & Knuckles, as you can juggle the Goal Post in the air for as long as you can after it falls from the sky in Act 1 of each stage.

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.
 * 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.
 * The tube waterslide in Chemical Plant works similarly to parts of Lost World.

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.
 * Omochao helps the player by giving tips in every level, except for the final boss fight, where Sonic's friends give tips to beat the boss.
 * 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 give him boost energy, just like in Rush.
 * Blaze is seen 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.
 * Each Sonic haveing thier own remix of the stage theme is just like how Blaze and Sonic both had thier own remix of each stages theme in this game.

Sonic Rush Adventure:
 * Blaze mentions that there are rings similar to Red Rings in 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 combo finisher Modern Sonic can perform originated from this game.
 * 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.
 * It is unknown how this game can be used at all, as the game's events were erased in the game itself. However, there are still possibilities for this.

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 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", which was her nickname for Sonic in Sonic Chronicles: The Dark Brotherhood.

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 continue on, otherwise they may find themselves stuck in an endless loop.
 * 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 beginning, just like in this the PS3/Xbox 360 version of this game while on the other hand, Modern Sonic already starts with all of his abilities in the console version of Generations, just like in the Wii/PS2 version of 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 ability in the Wii/PS2 version which could be deflected back at it.
 * 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.
 * Modern Sonic enters Casino Night falling from the sky, just like he did in every daytime stage in the Wii/PS2 version of this game.
 * Wentos' Chao puppets are seen hanging in the Skill Shop.
 * The Console/PC version of this game uses the Homing Attack lock on icon from this game.

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.
 * Silver appearing in Tropical Resort is also a reference to the DS version of the game, since he was wandering around the park with Blaze in that game.
 * The face of the Time Eater before being revealed has a similar look to the Violet 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, just like both bosses did in Sonic Colors.
 * In the handheld version of Generations, Tails gave hints to the Sonics instead of Omochao. Throughout this game whenever the player activates a hint, Tails would give him the advice.
 * The 3DS version of the game uses the Homing Attack target lock icon from this game.

Sonic Channel:
 * If the player gets an A rank with Modern Sonic, he'll do one of the many poses that he has in 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.

Merchandise
The game had two newly revealed action figures at Comic-Con 2011. Also, Nintendo released official Sonic Generations shirts to mark Sonic's 20th birthday. Jazwares released a line of Generations themed toys (fittingly called their "20th Anniversary" line), from a character with an iconic badnik with a picture of a stage to giant stuffed animals.

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 the Sonic Colors manga.

Trivia

 * This is the first Sonic game for the Nintendo 3DS.
 * The textures for Planet Wisp's environment map are actually screenshots of the team's dev program.
 * 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.
 * All Challenges against friends in the Classic Era are races.
 * Tails is the only character who races against Modern Sonic. Knuckles and Amy race against Classic Sonic.
 * This is the first 3D Sonic game not to have a unique 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.
 * Classic Tails' artwork seems to have "buckles" under his socks (above his shoes).
 * Like Sonic Unleashed (Wii/PS2), when using the Sonic Boost on a Dash Panel, Sonic performs a spin dash animation.
 * In both Sonic & Knuckles and Sonic Generations, the Death Egg can be seen in the background of Sky Sanctuary. In Sonic & Knuckles, the next level is Death Egg Zone, and in Sonic Generations, the next level is the fight against the Death Egg Robot, which ironically takes place in Death Egg.
 * This is the first time Modern Sonic gets Boost Energy from both Rings and Enemy Power in a handheld console.
 * The console/PC versions have a white colored design on top and bottom, where as the 3DS version has a  blue design. Coincidentally, the consoles and handheld's version's Japanese names are "White Time and Space" (console/PC) and "Blue Adventures" (3DS).
 * The rivals in this game 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 rivals that battle Sonic.
 * In the console/PC version, the drowning countdown 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.
 * Neither of Speed Highway's main acts include the At Dawn Section from Sonic Adventure. However, one Challenge Act with Cream shows the stage at dawn.
 * 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 product, he doesn't.
 * If a ring item box is destroyed in the Console/PC version, the sound when the player gets a Ring sounds ten times instead of one. In the 3DS version however, it only just sounds once.
 * 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. This most likely references 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.
 * 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) and Speed Highway (Knuckles' first level). 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.
 * 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, which was the game where Eggman got his nickname.
 * Metal Sonic's artwork pose is similar to Shadow's.
 * This is the second 3D Sonic game in which player starts a new game and are taken to the first stage, rather than showing the cutscene first. The first game is Sonic Colors.
 * In the 3DS version, Classic Tails suddenly appears after the boss battle with the Death Egg Robot/Big Arm. Takashi Iizuka said that there 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.
 * Coincidentally, Shadow's line from his own game, "Where is that damn fourth Chaos Emerald?" is also reference, as he has the fourth Chaos Emerald of the game.
 * 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 (Seaside Hill), the 3DS version considers it part of the Modern Era (Egg Emperor).
 * 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).
 * 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, 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 hub world, Sky Sanctuary has trees with grapes in them. Knuckles' favorite food is stated to be grapes in the Sonic the Hedgehog 3 manual, and Sky Sanctuary is also where Knuckles is saved in Sonic Generations.
 * 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. Considering the fact that the plant was heavily damaged in the modern stage, this is probably reconstruction.
 * 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.
 * 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 & Knuckles.
 * 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.
 * This is the second game to use skill customization, the first being Sonic and the Secret Rings.
 * 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 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. Both stages represented the Dreamcast era.
 * In the console and PC versions, it takes about five 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.
 * This is the first modern Sonic game on a handheld Nintendo system not to have Boost Mode.
 * This is the only anniversary title that didn't introduce another hedgehog character to the series. Shadow was introduced in Sonic Adventure 2 (tenth anniversary) and Silver was introduced in Sonic the Hedgehog (2006) (fifteenth anniversary).
 * In the Console/PC version, Omochao works as a guide by giving advice 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.
 * Orcas appeared in both versions of the game, in Seaside Hill (360/PS3/PC) and Emerald Coast (3DS).
 * 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.
 * 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.
 * Even if the player lives in North America, the PC version downloadable from Steam is based on the PAL version. This is confirmed due to "Colors" being spelled "Colours".
 * In the Unlockable Songs list, Hydrocity Zone is spelled "Hydro City Zone" instead.
 * Silver is the only rival or boss that is never faced at his original location in either version of the game. (Silver is fought in Crisis City in the console versions, and Tropical Resort in the 3DS version.)
 * Sonic Generations can be considered similar to Sonic 06, mainly since there is a creature (Sonic 06 had Solaris, while Generations had Time Eater) that devours time and the events of the game were erased in both games. Coincidentally, both are anniversary games.
 * In the 3DS version, many of the levels are direct remakes of previous acts. For example, Classic Sonic's Act of Green Hill, Casino Night and Mushroom Hill are taken straight from Act 1 of their respective games. Modern Sonic's Water Palace also resembles Act 1 of its counterpart in Sonic Rush, and Classic Sonic's Tropical Resort is a reconstruction of Act 1 of the DS Sonic Colors.
 * During the credits, the original levels from each game play along with the music medley as a tribute to the original games. In the console/PC version, the following game versions were used: the original Japanese Sonic Adventure release on Dreamcast, Sonic Adventure 2 Battle on GameCube, PC version of Sonic Heroes, the PS3 versions of Sonic 06 and Sonic Unleashed, and the Wii edition of Sonic Colors. There are no obvious indications if the Genesis/Mega Drive games are originals or direct emulations (or even Sonic Jam). Oddly enough, even though the credits use the revised Japanese version of the original Sonic the Hedgehog, the unlockable emulation in console versions is the original American release.
 * Sonic Generations was held on a 66% discount on Steam via PC Download as a Daily Deal due to the large amount of downloads.
 * In Sonic the Hedgehog 2, Chemical Plant is the second stage, in this game, coincidentally, Chemical Plant is the second stage.
 * In the Collection Room, two of the cutscenes you can view are both named Eggman Abducted, both being the cutscene after beating the Death Egg Robot and the Egg Dragoon.
 * Time Eater being initially believed to be the main antagonist only for Eggman to reveal himself as the true main antagonist near the end is a reverse twist to most 3D Sonic games; in which Eggman is initally believed to be the villain only for a another enemy to be revealed as the true enemy towards the end.
 * This is later done in the Mario series as well, where Mario & Luigi villains tend to overshadow Bowser as the main villain, but in Mario & Luigi: Dream Team, Bowser betrays Antasma and is the final boss.
 * When modern Sonic says "No stranger then rescuing genies and magic books or saving aliens in a interstellar amusement park," he is referring to Sonic and the Secret Rings and Sonic Colors respectively.
 * Eggman Nega is the only one of the series' main characters to be completely absent, not even having a mentioning or reference.
 * In the Console/PC version, the rival and boss battle of the Dreamcast era mainly used the Boost throughout the fight which was introduced in the Modern era (Sonic Unleashed).
 * In contrast, the rival and boss battle of the Modern era mainly used the Homing Attack and Auto-Running  which were introduced in the Dreamcast era games (Sonic Adventure) .
 * Not long before the release date of Sonic Generations, Sega sponsored a skateboarding sporting event that took place in Venice Beach of California named "Sonic Generations of Skate".
 * The game also shows how Sonic's skills are improving, showing his previous way of taking only slightly difficult routes (Classic Sonic), and then showing how he now goes through the truly difficult ways of the Act (Modern Sonic).
 * Four of the levels were the first levels in their original games. Green Hill Zone, City Escape (Hero Story), Seaside Hill (Team Dark and Team Chaotix stories), and Crisis City (Silver's Story)
 * The Silver the Hedgehog boss battle is the only recreated/reimagined boss in the game that wasn't based off a second to last or final boss. Metal Sonic, Egg Emperor,and the Egg Dragoon are boss battles that are second to last while the Death Egg Robot, Big Arm, Shadow the Hedgehog (Final boss of Hero story in Sonic Adventure 2), and Perfect Chaos are all final bosses to their story modes and games.
 * The Console version of Sonic Generations draws heavy inspiration from the DS version of Colors while the 3DS version draws it's inspiration from the Wii version of Colors.
 * In the console version, when looking at the models on the character profiles, both Silver and Rouge strike the same pose.
 * If you view the entire White World in a 3D model viewer, if you zoom out and look around, the entire Crisis City level will be there.
 * On the console/PC version, in the cutscene were everyone is teleported back to their world, when Classic Sonic and Classic Tails go through the portal back in time, an image of Green Hills Zone is shown, even though Tails was never in Sonic the Hedgehog, which was when Green Hills Zone made it's first apperance. Therefore, Tails would have disappered, unless it was in after the time Sonic the Hedgehog 2.
 * When not talked to for long enough Modern and Classic Tails will yawn like they did in Sonic the Hedgehog 2.
 * When both Sonics transforms into Super Sonic, an instrumental remix of Sonic the Hedgehog 4: Episode I theme can be heard.