Sonic the Hedgehog series

The Sonic the Hedgehog series is a franchise of video games released by Sega starring their mascot character Sonic the Hedgehog. The series began in 1991 with the release of Sonic the Hedgehog on the Sega Mega Drive/Genesis. An 8-bit version of the game was also released for the Master System and Game Gear formats. Sonic was responsible for turning Sega into a leading video game company during early in the 16-bit era, and his first game soon replaced Altered Beast as the default pack-in game for the Genesis in North America and Europe. As of May 2006, the franchise has sold more than 44 million units, with three more games released in the later half of 2006.

Games in the series are developed by Sonic Team, with the exception of some spinoffs that were independently developed by Sega of America. The main programmer for the first game was Yuji Naka, who would later become head of the Sonic Team division, and the game planner was Hirokazu Yasuhara. The music of the first two Sonic the Hedgehog games on the Mega Drive/Genesis were composed by Masato Nakamura of the Japanese band Dreams Come True.



Overview
Nearly all games in the series feature a teenage hedgehog named "Sonic the Hedgehog" as the central [layer character and protagonist. The games feature Sonic's attempts to save his planet from various threats, primarily the evil genius Dr. Ivo "Eggman" Robotnik. The main antagonist throughout the series, Robotnik's aim is to rule the planet and establish the Eggman Empire; to achieve this, he usually attempts to eliminate Sonic and acquire the powerful Chaos Emeralds.

History
Most two dimensional Sonic titles are platform games viewed from a side-on perspective. Their controls are fairly basic and do not deviate much from the genre standard; the selling point of the series is the incredible speed of the playable characters, who usually have the ability to run uphill, walls, and even ceilings. Roller coaster-like loops and corkscrews are also common in Sonic games, as are giant pinball machines with flippers and bumpers which knock Sonic around like a ball. The stages are also similar to roller coasters in that many sequences involve Sonic being thrown along pre-set paths with little input from the player, which has led to criticism that the player can complete a Sonic game merely by holding the pad in one direction. However, the games also feature numerous sections involving precise jumping between platforms and avoiding of hazards, although these sections do not require "pixel-perfect" judgement and are perhaps more lenient than most platform games of the era.

The Sega Technical Institute tried to develop a "true" Sonic game for the Saturn called Sonic X-treme. This game was intended to compete with Nintendo's Super Mario 64. However, due to time constraints and issues between STI and the Japanese division of Sega and Sonic Team, the project was cancelled in the last months of 1996.

Sonic 3D: Flickies' Island, an isometric, pseudo-3D ("2.5D") game, was released for the Mega Drive in 1996. Sega Saturn and Windows PC conversions followed to cover the hole of the cancellation of Sonic X-treme. They had enhanced graphics and a different sound track, composed by Richard Jacques. Sonic 3D was developed by Traveller's Tales, although Sonic Team worked on the Special Stages in the Saturn/PC version.

In 1997, a compilation entitled Sonic Jam was released for the Saturn. In addition to containing Sonic the Hedgehog, Sonic 2, Sonic 3 and Sonic & Knuckles, it also included a "Sonic World" mode. This allowed the player to control Sonic in a small 3D world similar to the Green Hill Zone from the original game; it contained no enemies and was mainly a means of accessing the disc's multimedia features such as BGM's, illustrations and even commercials.

The full leap into 3D platforming was made with Sonic Adventure, a launch title for the Sega Dreamcast console. On 19 June 2001 in North America (23 June in Japan and Europe; the 10th anniversary of the US release of Sonic the Hedgehog), Sonic Adventure 2 was launched. Both of the Adventure titles were later ported to the Nintendo GameCube (under the titles of Sonic Adventure DX: Director's Cut and Sonic Adventure 2: Battle) when Sega dropped out of the hardware market. DX was also ported to Windows PCs.

The first Sonic game to release simultaneously on multiple consoles, Sonic Heroes, was released on the GameCube, Sony PlayStation 2 and Microsoft Xbox in December 2003 in Japan, with American and European releases following soon after, and a PC version the following November. The platforming was largely similar to that of the Adventure titles, although the player now controlled the lead character of a team of three themed characters, with the other two following closely behind (similar to the later Sega Mega Drive games). The player could switch to a new leader at any time, in order to make use of each character's special skills. It sold well, but opinions among both reviewers and fans of the Sonic series were mixed.

Shadow the Hedgehog was no different. Released in the US in November 2005, it received mixed reviews. X-Play, for instance, had given it a 1 out of 5, making it the lowest-scoring Sonic game reviewed on the show. Other game sites such as IGN and GameSpot similarly panned the game. One of the greatest controversies revolving around this game is the gunplay; some fans insisted that Shadow was the self-proclaimed "ultimate life-form" and did not need a weapon. Nintendo Power and Gametrailers, however, both rated it above 8 out of 10. Two other controversies were the over-use of the [curse word "damn" and the fact that Sega had decided to switch to the voice artists from the English version of Sonic X.

A highly faithful two-part port of Sonic the Hedgehog made for mobile phones has been a huge hit in Europe, introducing the game to a new generation of pre-teen gamers, with respected handheld specialist Pocket Gamer awarding Sonic the Hedgehog Part Two a 9 out of 10 review score.

Other gameplay styles
A few Sonic games focus on gameplay styles other than the standard platforming. The first of these was Sonic Spinball (released on the Mega Drive in 1993 and on the Master System and Game Gear in 1994). The concept of Sonic bouncing around as the ball in a giant pinball table had been used in both Sonic the Hedgehog and Sonic the Hedeghog 2; Sonic Spinball made a whole game around that premise.

Several racing games starring Sonic characters have been developed. In Sonic Drift and Sonic Drift 2, characters rode go-karts (kart circuits were later included in the two Sonic Adventure games). In Sonic R (1998), most characters ran on foot (with Eggman riding his Eggmobile and Amy driving a car), while in Sonic Riders (2006), they race on hoverboards. A race mode was also included in Sonic Adventure 2 Battle.

Sonic Shuffle was a Mario Party-style virtual board game/party game for the Sega Dreamcast.

Edutainment videogames starring Sonic and Tails have also been released, such as Sonic the Hedgehog Gameworld and Tails and the Music Maker for the Sega Pico, and the PC title Sonic's Schoolhouse.

A fighting game named Sonic the Fighters existed as an arcade game, and later a fighting/platform game hybrid called Sonic Battle was released for the Game Boy Advance.

In 1993, Dr. Robotnik's Mean Bean Machine was released for the Sega Mega Drive. The game was basically a clone of a Japanese puzzle game named Puyo Puyo. This game was also ported to the Game Gear.

Rings
For information on the Rings featured in the cartoon series and comics, see main article. One distinctive and recurring feature of Sonic games are the collectible golden Rings (sometimes referred to as Gold Rings or Power Rings) spread throughout the levels. This gameplay device allows players possessing at least one ring to survive upon sustaining damage from an enemy or hazardous object. Instead of dying, the player's rings are sacrificed; in most Sonic games, a hit will cause the player to lose all of their rings, although in certain situations (such as the Special Stages in Sonic the Hedgehog 2) and throughout certain games (such as Sonic Triple Trouble, Shadow the Hedgehog and Sonic Blast) a hit only costs a set number of rings rather than the entire collection.

Upon colliding with a hazard, the on-screen character is thrown backwards and given a momentary period of invulnerability (represented by a rapid flashing between visible and invisible). The dropped rings burst out of the character in a circular pattern and bounce around the environment, flashing for a few seconds before disappearing entirely. During this brief period, it is possible for the player to recover some of the rings they lost. Generally fewer "recoverable" rings are displayed on-screen than the number actually lost (usually a maximum of around 20; fewer in Sonic games on 8-bit consoles, about 50 in Sonic Rush).

Certain causes of death cannot be prevented by holding a ring, including being crushed, falling into a bottomless pit, and drowning.

In line with many platform games, collecting 100 of these common collectibles will usually reward Sonic with an extra life. Certain titles in the series often reward the collection of other quantities of rings, often in conjunction with the Chaos Emeralds; usually, at least fifty Rings are required to access the Special Stages in which the Chaos Emeralds may be obtained, or to utilize a character's super transformation.

The origin of the rings, like the Chaos Emeralds, is never revealed during the game series. They are not often referenced by characters during gameplay, but they are used as currency in Chao Black Markets and and in shops in Sonic the Hedgehog (2006). In Shadow the Hedgehog, Dr. Eggman collects them for prizes in his game-filled carnival base, and is distressed when Shadow takes them from him during the "Egg Dealer" boss battle.

Giant Rings
Whereas most Rings were small and easily collectible, certain Rings appeared that were much larger. The so-called "Giant Rings" were hidden in the stages and designed to be jumped through, which would transport the character to a Special Stage, where the character could collect one of the Chaos Emeralds or, in certain circumstances, Super Emeralds. They were used for this purpose in the games Sonic the Hedgehog, Sonic CD and Sonic the Hedgehog 3 & Knuckles. Sonic the Hedgehog 2 used Star Posts instead. In Sonic the Hedgehog 3, if all the Emeralds had already been found, these rings could be collected for fifty rings each, allowing the characters to easily tap into the power of the Chaos Emeralds (usually becoming Super, or Hyper in Sonic 3 & Knuckles if the player has collected all the Super Emeralds as well). In most of the newer games since Sonic Adventure 2, these giant rings have taken the place of the old signposts as the end level marker and touching it would end the level.

Chaos Emeralds
The Chaos Emeralds are seven emerald]]s with mystical powers, and a recurring feature of Sonic games. They are the basis of most of the games' plots, and the player is frequently required to collect them all in order to fully defeat Eggman and achieve the games' "good endings", super forms, or both. The method used to acquire the Emeralds differs between titles in the series. Most early games require the player to find them in Special Stages. In some games, such as Sonic R and the 8-bit versions of Sonic the Hedgehog and Sonic the Hedgehog 2, they can be found in hidden locations within the main levels. In most later games, the Chaos Emeralds are found by the characters throughout the games' story modes, and do not need to be "found" by the player.



Master Emerald
The Master Emerald resides in a shrine on Angel Island and is guarded by Knuckles the Echidna; it contains an unknown amount of power, possibly equal to or greater than all 7 Chaos Emeralds, and is used to keep the Angel Island afloat in the sky. The Emerald also has the power to fully control everything that the Chaos Emeralds do, including the ability to negate the energy of the Chaos Emeralds, as seen in Sonic Adventure and Sonic Adventure 2, or empower them, as seen in Sonic the Hedgehog 3 & Knuckles. The Master Emerald can also be used to power mechanical devices, and has been coveted by Dr Eggman since his discovery of it. During Knuckles' final boss fight in Sonic the Hedgehog 3 & Knuckles, Mecha Sonic powers up using the Master Emerald into a quasi-Super form.

Special Stages
Usually, a Chaos Emerald may be earned in a Special Stage or Special Zone. Special Stages usually take place in surreal environments and feature alternate gameplay mechanics to the standard platforming of the main levels: the 16-bit Sonic the Hedgehog  consisted of a giant rotating maze (which many considered a major technical achievement); Sonic the Hedgehog 2, Sonic 3-D Blast, Sonic Heroes and Sonic Rush featured "in your face" segments with the hedgehog running along a long tunnel, with a variant of this used for Knuckles Chaotix, Sonic Advance, and Sonic Advance 3; 3-D "collect items" levels, as in Sonic 3 and Sonic & Knuckles, which used the same perspective but had Sonic collecting all the blue-coloured orbs on the surface of a giant sphere, and a different version, the 3-D ring-collecting Special Stage, used in Sonic Advance 2. Sonic Chaos (Sonic and Tails in Japan) utilised a variety of gimmicks for its levels.

Some Sonic titles include Special Stages, but not as a means of collecting Chaos Emeralds. As the Emeralds of the 8-bit version of Sonic the Hedgehog were hidden in the main stages, the game's spring-filled Special Stages were merely used as a means of adding variety, and for a player to increase their score. Similarly, Sonic 3 and Sonic & Knuckles, in addition to their main Special Stages, featured entirely optional bonus stages, one of which combined the rotating maze of the 16-bit Sonic the Hedgehog with the pinball gambling of Sonic the Hedgehog 2, and Sonic Heroes had an alternate Special Stage for earning lots of 1-UPS, very much like the one in which Chaos Emerals are collected, but with the objective being to get to the Goal Ring before time ran out, rather than catching up to the Chaos Emerald at the end of the tunnel.

Just as the design of the Special Stages has changed, so has the means of accessing them. In Sonic 3 & Knuckles, giant rings were hidden in levels to take the player to the Stages, but most other titles involve the collection of a certain number of rings, usually 50. In both the 8- and 16-bit versions of Sonic the Hedgehog, they were reached by finishing a level with more than 50 rings; the player would then have to jump inside the giant ring that would appear just after the goal post. In the 16-bit Sonic the Hedgehog 2, reaching a Star Post when they held this number would create a warp of stars which would take a player to the Special Stage when jumped through. Sonic 3D required the player to deliver rings to Knuckles and Tails, who could be found within each level. Sonic Chaos changed the figure, with access to a Special Stage being the reward for collecting 100 rings.

In the more recent game Sonic Heroes, the Special Stages made a return. These special stages were accessed by finding a key in stage 2 of each zone and keeping it (by not taking damage) until the end of the level. It consisted of running through a twisting tube. The Chaos Emerald would be ahead of the characters, and the goal was to "catch up" with it by collecting orbs which refueled a "dash gauge" which the characters would use to speed up and catch it. The stages had some motion glitches which would sometimes cause the characters to slow down dramatically, making it difficult to complete the stage. If the Chaos Emerald got to the end of the stage before the characters caught up with it, the stage would end without the gaining of a Chaos Emerald.

Super Sonic


Since the 16-bit version of Sonic 2, Sonic has had the ability to transform into the extremely fast and nearly invulnerable Super Sonic once all seven Chaos Emeralds are collected. After that, Super Sonic can be used in any of the following levels once 50 rings have been collected, although one ring is lost for every second Sonic remains in this form.

In the Sonic Adventure titles, the Special Stages were omitted entirely and Chaos Emeralds were collected in non-interactive cut-scenes as part of the story, with Super Sonic only appearing in the climactic final boss fights. This dismayed many fans, who appreciated the additional replay value offered by retrying a game's levels with Super Sonic's additional abilities. Despite several games since returning to the emerald-collecting of the 2D platform titles (including the Advance series, Heroes, and Rush), Super Sonic was again only playable at the end of the game in an extra zone.

In Sonic Riders, Super Sonic is also an unlockable character, playable outside the final level for the first time since the Sega Genesis games. As with previous games, Super Sonic consumes rings as long as the form is sustained, and Sonic reverts to standard Sonic when he runs out of rings. He is playable by unlocking the "Chaos Emerald" gear.

Other characters have also been able to utilize the Super transformation. In Sonic & Knuckles, Knuckles the Echidna could also transform into Super Knuckles. By locking-on Sonic 3 to Sonic & Knuckles, Hyper Sonic, Super Tails and Hyper Knuckles also become available, by collecting all 7 Super Emeralds in addition to the 7 Chaos Emeralds. In Sonic Adventure 2, Super Shadow also appeared at the end of the Last story, who fought alongside Super Sonic to destroy the Biolizard. In Sonic Rush, Burning Blaze appears for the extra boss, similar to the end of Sonic Adventure 2. It is named "Burning" instead of "Super" as she uses the Sol Emeralds instead of the Chaos Emeralds. In Sonic the Hedgehog, Super Silver appears along with Super Sonic and Super Shadow.

Music
The music of the Sonic series is considered one of its strongest aspects. Sonic games have featured tunes composed by a variety of people; Masato Nakamura of J-pop band Dreams Come True was responsible for the music of the first two 16-bit games. Ys/Streets of Rage composer Yuzo Koshiro composed the music for the first 8-bit title, barring what was taken from the 16-bit title. Sega's in-house music company, Wavemaster, did the majority of the music in later titles. One Wave Master employee, Jun Senoue, is part of the band Crush 40, and through his ties to the band they have played the main theme tunes of the two Sonic Adventure games, Sonic Heroes, and Shadow the Hedgehog. Heroes and Shadow the Hedgehog also featured other bands, such as Julien-K. Richard Jacques, a frequent composer of music for Sega's games, contributed to the soundtracks of Sonic R and the Saturn/PC version of Sonic 3D Blast: Flickies' Island.


 * See also: List of Sonic the Hedgehog series songs

Characters
Since Sonic's first appearance in 1991, many more characters have appeared, and most of them have been added to main cast. Many of these characters have garnered steady fanbases since their inclusion into the franchise, while other longtime fans have criticized them for allegedly taking the gameplay focus off Sonic. Here are the main characters arranged in order of appearance:

Sonic the Hedgehog: The series' principal hero. Sonic possesses incredible super speed and numerous other abilities, and uses his skills to save the world from Dr. Eggman. He is impatient, laidback, confident and always on the look-out for an adventure.

Dr. Eggman: Also known as Dr. Robotnik, Eggman is Sonic's arch nemesis and the series' main villain. He is extremely intelligent, egg-shaped, and has a giant brown moustache. Eggman is an expert in robotics and wishes to conquer the world and build the Eggman Empire. However, Sonic and his friends always stand in his way. In many cases, his own plans ironically out do himself.

Miles "Tails" Prower: Sonic's best friend. He is a two-tailed fox who can fly for a limited time by spinning his tails rapidly. He is a skilled mechanic and often takes care of Sonic's plane called the Tornado. He pilots a machine called the Cyclone, which is an upgraded version of the Tornado with battle-mech capabilities.

Amy Rose: A pink hedgehog who has become Sonic's self-appointed girlfriend, first seen in Sonic the Hedgehog CD. Ever since Sonic and Amy met, she has been in love with Sonic and she now wants him to marry her. Amy is quite strong and smashes enemy forces down with her trusty Piko Piko Hammer.

Metal Sonic: The robotic counterpart of Sonic the Hedgehog, who is created by Dr. Eggman. He seems to believe that he is in fact the true Sonic, and that Sonic is his copy. In Sonic Heroes he betrayed his creator, and took the task of trying to achieve world domination into his own claws.

Knuckles the Echidna: The last living echidna, and Sonic's hotheaded friend and rival. Knuckles resides on Angel Island, where he guards the Master Emerald, the source of the island's ability to float in the sky. Knuckles is very strong; his spiked fists are capable of smashing through boulders as well as allowing him to climb walls. The nature of his echidna spikes allows him to glide in the air for periods of time.

Chaotix: A team of misfits who have started their own detective agency. The Chaotix consists of Vector the Crocodile, Espio the Chameleon and Charmy Bee. They met for the first time when they fought against Dr. Eggman in Knuckles Chaotix, along with Mighty the Armadillo.

Big the Cat: A big purple tabby cat who loves fishing. His best friend is a frog named Froggy, who he constantly keeps losing. Big lives with his buddy in a peaceful hut in the Mystic Ruins.

E-102 Gamma: A robot created by Dr. Eggman. Originally a part of the E-Series, he, thanks to Amy Rose, became good spirited and decided to save his friends. In the end, he was destroyed by E-101 Beta.

Shadow the Hedgehog: Shadow is a mysterious, black hedgehog resembling Sonic in appearance and skills. He is the Ultimate Lifeform created by Gerald Robotnik and Black Doom on the Space Colony ARK over five decades ago. He recently suffered from amnesia but has regained all of his memories since. He can use Chaos Control to distort time and space.

Rouge the Bat: Rouge is a treasure hunter and a spy for GUN. She is full of feminine charm and can be very manipulative. She is Knuckles' rival.

Cream the Rabbit: A naive young rabbit who lives with her mother, Vanilla. Cream's best friend is a Chao called Cheese (which she uses as missile). Because Cream has been brought up like a princess, she does not like being involved in other peoples' affairs. She can fly using her large ears.

E-123 Omega: An robot created by Dr. Eggman. He is the last of the E-100 series of robots and seeks revenge on Eggman for shutting him down. Rouge accidentally activated him when trying to free Shadow from Eggman's base. Since then, he has became good friends with both of them.

Blaze the Cat: A female, pyrokinetic, lavender cat from Silver's time period. As guardian of the Sol Emeralds, it is her duty to prevent anyone from taking them away from her. She is somewhat shy, and tends to conceal her real feelings.

Silver the Hedgehog: A mysterious hedgehog from the future. Silver traveled through time to stop Sonic, who he believed to be the Iblis Trigger. Unlike Sonic, he does not possess speed but instead utilizes psychic powers.

Regional variations
To create distinctive Sonic products in various markets, Sega initially developed two different back-stories for the instruction booklets &mdash; one story for the Japanese manual, and another story for all other regions. For example, although "Dr Eggman" has always been the antagonist's name in Japan, he was originally called "Doctor Ivo Robotnik" in North America, Europe, Australia, and New Zealand. Also, in the Japanese manuals, it is said that the games are set on Earth, specifically, on islands in the Pacific; however, according to some English manuals printed before 1999, the games are set on a planet called Mobius. Nevertheless, despite these location differences, all games had the same gameplay.

At the beginning of the Dreamcast era, Sonic Team decided that there was a need to chose one particular version of the canon to expand on in the newer generation of games. They chose the Japanese canon, making it the "new" international canon and thus discontinuing the "old" western version. An alternative angle might be to suggest that Sonic Team came up with their own canon, one that did away with both the Japanese and the western versions of the old canon. However, it is clear that even under these considerations, the new canon borrows so heavily from the old Japanese canon that the differences are negligible.

Chronology
There is a relatively simple criteria upon which a game's relative canonicity and chronology is determined: the higher a game is cited by other games or cites other games, the more it fits into the existing canon. The games Sonic 1, Sonic CD, Sonic 2, Sonic 3, Sonic & Knuckles, Sonic Adventure, Sonic Adventure 2, Sonic Heroes, Shadow The Hedgehog, Sonic Riders and Sonic the Hedgehog are absolute canon to the ongoing continuity, since they were directly created by Sonic Team, or in-house by Sega. The Sonic Advance series, Sonic Battle and Sonic Rush are canon to a lesser extent, mainly because they were out-sourced from Sega and Sonic Team. At times they make weaker ties to earlier games, and also tend to receive few ties in return. Most other games with Sonic-based titles are generally considered canonical as well, unless they explicitly contradict the Sonic Team games; however, this is an inconsequential point, as these games rarely had any influence on the main series in comparison.


 * Sonic the Hedgehog – (Genesis) (1991)
 * Sonic 1 is the first game in the series and establishes the canon's foundation. It introduces the protagonist, Sonic the Hedgehog; the antagonist, Dr Eggman; basic gameplay elements; and bosses that have reappeared in later games, such as in Sonic Advance.


 * Sonic the Hedgehog CD – (Sega CD) (1993)
 * Sonic CD comes next because Tails is conspicuously absent &mdash; he has appeared in every canon Sonic game since his introduction in Sonic 2. Placing CD after Sonic 2 creates a discontinuity. Additionally, Tails appears in a hidden picture accessible using the debug code saying 'See you next game!' &mdash; a hidden easter egg that refers to Sonic 2, not Sonic Drift (it is believed so since Tails is standing next to a car), because Sonic Drift is not canon. And finally, Sonic CD was supposed to be released either at the same time or before Sonic 2, but due to considerable delays, it was released after Sonic 2. Since games in the Sonic series generally happen more-or-less in order of release, Sonic CD occurs before Sonic 2.


 * Sonic the Hedgehog 2 – (Genesis) (1992)
 * The instruction booklet indicates that Sonic 2 comes after the events of Sonic 1. The game features new sprites for Sonic who appears to be slightly older, and also introduces Tails, Sonic's sidekick.  Super Sonic makes his first appearance.


 * Sonic the Hedgehog 3 & Knuckles – (Genesis) (1994)
 * Sonic 3 and Knuckles closely follows Sonic 2 and recycles its sprites and game engine core. Inside the game, Sonic's story happens first, then Knuckles' story.  In Sonic's story, Angel Island is in the sea and Knuckles is his enemy; in Knuckles' story, Angel Island is floating in the sky and Sonic is his ally.


 * Sonic Advance – (GBA) (2001)
 * While some may assume Sonic Adventure comes first, Sonic Advance comes first for two clear reasons: (1) Sonic's red Tornado biplane appears in it, but it was shot down and destroyed in Sonic Adventure; (2) In all the games after this game, including Sonic Adventure, Eggman has a much more complicated way of taking over the world, but in Sonic Advance 1 and 2, Eggman has the same old scheme: keep Sonic distracted with his robots while he tracks down the Chaos Emeralds.


 * Sonic Advance 2 – (GBA) (2002)
 * There are three reasons why Sonic Advance 2 occurs here. It is evident from the game and official material that Sonic Advance 2 closely follows it's prequel.  In Sonic Adventure's GameCube remake, Cream has a cameo appearance when she gives Sonic the Ice Stone, whom she met in this game.  The third reason is that Eggman's strategy is essentially unchanged from Sonic Advance.


 * Sonic Adventure – (Dreamcast) (1998)
 * Adventure marks the first of the fully 3-D and evolved Sonic games, and it is closely connected to Sonic & Knuckles, as seen by the fall of Angel Island. It also makes several references to earlier games: Sonic making jokes at Knuckles' expense about his history with Eggman; Tails' dream of when he first met Sonic; and Amy's flashback of when Sonic first rescued her from Eggman's base on the Little Planet while being chased by Metal Sonic.


 * Sonic Adventure 2 – (Dreamcast) (2001)
 * It is Sonic Adventure's sequel, and the events within closely follows it's prequel. This game introduces Shadow the Hedgehog as Sonic's cold-hearted rival.


 * Sonic Heroes – (GameCube, PS2, XBox) (2003)
 * It continues the storyline of Sonic Adventure 2. The game stars Metal Sonic as the antagonist of the game instead of Dr. Eggman.  In Team Dark's story, Shadow begins his story inside a cryogenic capsule; Rouge is surprised that he is still alive.  In Team Rose's story, Amy begins her story relaxing at the beach in a scene reminiscent of the opening cut-scene of Sonic's story in Adventure.


 * Shadow the Hedgehog – (GameCube, PS2, XBox) (2005)
 * It makes several references to Sonic Heroes, and, in Sonic Battle, Shadow is completely aware of his past and rants on about trusting in Maria, but in this game, he can only remember one tidbit of his memory, and, he doesn't even know who Maria is. "And who is this 'Maria'?" &mdash; Shadow the Hedgehog


 * Sonic Battle – (GBA) (2003)
 * Even though this game was released before Sonic Heroes, it comes after, because Rouge comments about E-102 Chaos Gamma (who she believes to be a Guard Robo) looking like Omega, whom she met in Sonic Heroes. "...that Guard Robo looked just like Omega" &mdash; Rouge the Bat. The second reason was explained above, in the case with Shadow's past.


 * Sonic Advance 3 – (GBA) (2004)
 * It is seen that this game closely follows Sonic Battle, and it continues Battle's storyline, seeing as Eggman found Emerl's pieces and re-built him into G-mel. Emerl is a robot introduced in Sonic Battle.


 * Sonic Rush – (DS) (2005)
 * It has to happen after Sonic Advance 3, because several elements introduced in Advance 3 are re-used in this game, such as Cream's house and the new looking Flickies. Blaze the Cat is introduced.


 * Sonic the Hedgehog – (XBox 360) (2006) (PS3) (2007)
 * It has to happen after Sonic Rush, because in this game, Blaze recognizes Sonic, whom she first met in Rush. "Blue Hedgehog......?" &mdash; Blaze the Cat. Silver the Hedgehog is introduced.


 * Sonic Rivals – (PSP) (2006)
 * Since the events of the previous game takes place in an alternate history, the main characters do not seem to recognize Silver at first, and he is re-introduced. This is the second canon Sonic game where Tails appears but not as a playable character, with Sonic Rush being the first.

So far the chronology of Sonic Riders and Sonic and the Secret Rings has not yet been confirmed. While Sonic Riders does not conflict per se with the previous games, it makes no references at all to events in earlier games. Secret Rings is currently under development and, if considered canon, would take place after Rivals. This is also because Silver and Blaze appear in the mini-games, although it is not known if they appear in Story Mode.

Spin-offs
The Sonic video game franchise has led to a large number of spin-offs starring Sonic. Each spin-off incorporates aspects from the games to varying degrees.

Animations
Adventures of Sonic the Hedgehog (or AoStH for short) is an American animated television series that was first broadcast in September, 1993, and has been running in cartoon syndication ever since. It follows the escapades of Sonic and Tails as they stop the evil Dr. Ivo Robotnik and his array of vicious robots from taking over the planet Mobius. The plots very loosely followed the storyline of the video games series; at the time the Sonic games were still quite new, and lacking much plot or character development, which was in turn filled in by the show's writers.

The animated television series simply called Sonic the Hedgehog originally aired from September 1993 to June 1995. While Adventures of Sonic the Hedgehog is known for its bright colors and whimsical humor, Sonic the Hedgehog featured darker stories which constituted a departure from the tone of the Sonic games of the time. To distinguish between the two series, fans typically refer to this series as SatAM because it was a Saturday morning cartoon while Adventures of Sonic the Hedgehog aired on weekdays in syndication, and using the show's full title would cause confusion in many situations because the show's title is the same as the character's name.

A two-episode OVA film series based upon the game Sonic CD and the video game series as a whole, Sonic the Hedgehog: The Movie was made in Japan in 1996 and released as a dub in North America in 2000. Unlike the games, the film takes place on a world named Planet Freedom that, as with many anime series, appears to be a crossbreed of a fairytale land and Earth. At the time of its creation, the anime did not differ as far from official canon as it does today; at this point, it could be considered to take place in an a different continuity than the games, just like other versions of Sonic from other media.

The cartoon Sonic Underground ran for only one season, 1998 to 1999; it bears little relation to other entries featuring Sonic (including previous games, comics and animated series), and shares few established characters. 65 episodes were originally produced, and of those, only 40 were released. Unlike it's predecessor, SatAM, the heroes do not remain in a sanctuary-like refuge but instead travel around Mobius to battle Robotnik's forces on a global scale. The Mobian civilisation featured in the series includes multiple cities, a poor underclass and an aristocracy for the heroes to interact with. Sonic Underground is the only animated series based on Sonic where Tails has not made an appearance.

The anime Sonic X is the longest-running and most successful animated series based on Sonic to date. Originally planned as a 52 episode series that would be inspired by the storylines of the Sonic Adventure series, Sonic X has now expanded to 78 episodes with the latest 26 episodes set primarily in outer space. The series borrows more from the games than any other Sonic cartoon before it; with the exception of Blaze the Cat, E-123 Omega, Babylon Rogues, Silver the Hedgehog, and Metal Sonic, every significant and playable video game character has made an appearance in the series. Sonic X is also the only animated series to include Super Sonic. Despite these similarities, it is not completely compatible with the video game canon if only for the fact that it shows Sonic being transported to Earth from another world; in the games, Sonic has always lived on Earth.

Comics
The Sonic the Hedgehog manga series, published in Shogakukan's Shogaku Yonensei (literally "fourth-year student") was written by Kenji Terada and it was illustrated by Sango Norimoto. The manga, which started in 1992, was about a hedgehog boy named Nicky who can turn into Sonic the Hedgehog. Sonic fights Dr. Robotnik, with Tails tagging along to help him.

Sonic the Comic, known to its many readers as STC, was a UK children's comic published by Fleetway Editions between 1993 and 2002. Although it was the UK's official Sega comic, Sonic the Comic established its identity and ongoing storyline and setting when Sonic, Tails and their friends were sent forward in time six months. During their absence, Doctor Robotnik successfully conquered the entire planet of Mobius, and Sonic's group were forced underground, operating as "freedom fighters" attempting to bring down Robotnik's rule of the planet. Due to an aggressive series of budget cuts on the part of Fleetway, the series went into full reprint by issue 184; the final story ended with a number of loose ends left untied. An online fan based comic, called STC-Online, has been set up to continue the STC story starting from where the origional STC story left off and begining with issue 224, due to STC being reprints from issues 185 to 223. It has recieved positive feedback from both fans and writers of the origionl STC.

Sonic the Hedgehog is an ongoing series of American comic books published by Archie Comics. All of Archie's Sonic-related series, miniseries and specials take place in the same fictional universe. This universe features a mixture of characters, settings and situations from the video games, the SatAM cartoon, the various other incarnations of Sonic, and many elements unique to the comic universe. The current status quo of the comic deals with a full-scale war between the Eggman Empire, ruled by Robotnik, and the restored Kingdom of Acorn, currently ruled by King Elias Acorn.

Sonic X is the title of an ongoing comic book series that exists to supplement the stories from the animated series of the same name. It began in September 2005 and was originally meant to be a four-part series; due to the positive reaction to the series' announcement, it was extended to ongoing status before the first issue premiered. The comic is unique in that it is not directly based on the games; the comic is based on the television show and takes place in its expanded fictional universe. The comic borrows elements from the series first two seasons of the show, including Eggman's fort, destroyed in Season One on the cartoon, and characters from the Sonic Adventure storyline.

Notes and references
In addition to information taken from the Sonic the Hedgehog games themselves, the instruction booklets of the US and Japanese versions of the games were also used as references for this article.