Sonic the Hedgehog

The 'Sonic the Hedgehog series is a series of video games first published in 1991 created by Sonic Team.
===Story===
The premise of the games revolves around Doctor Eggman (Doctor Ivo Robotnik in the earlier releases in North America, Europe, Australia and New Zealand) trying to take over the world by turning the animals into robots (often called Badniks, though this is an US/EUR term and hasn't been used since Sonic Adventure). Sonic is charged with saving them. In later games he is joined by Miles "Tails" Prower, Amy Rose, Knuckles the Echidna, Cream the Rabbit and a host of other characters. He usually collects the Chaos Emeralds (usually from the Special Stages) in order to achieve the best ending in the game, as well as become his most powerful form, Super Sonic, from Sonic 2 upwards. In this state, he is completely immune to all enemies and obstacles (although he can still be killed by falling into pits, being crushed and drowning), gains the ability of flight in certain circumstances, and the unique skill of breathing in space. However, Sonic's quest does not necessitate collecting the Emeralds himself; he must only prevent Eggman from getting them and dooming the world with their power, as well as deal with numerous other foes, such as Metal Sonic (and Mecha Sonic), Void, Fang the Sniper (formerly Nack the Weasel in the West, still Nack in the comic books). Shadow the Hedgehog and Rouge the Bat generally oppose Sonic, but will assist him if the situation calls for it.
===Gameplay===
Most Sonic titles are platform games viewed from a side-on perspective. Their controls are basic and do not deviate much from the genre standard; the selling point of the series is the sheer speed of the playable characters, who usually have the ability to run on slopes, 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.
In order to progress through his missions, Sonic must collect rings to protect himself from enemy robots and traps; as long as he has at least one ring he is invulnerable to dangers, although he will lose all of them if an attack does get through. Most Sonic games allow him to recover many of these scattered rings during a brief "invulnerable" period. However, rings do not protect against all hazards: he can still drown, be crushed or fall to his death. In line with many platform games, collecting 100 of these common collectables will reward Sonic with an extra life.
Often a certain number of rings (usually 50) are required for Sonic access the Special Stages, where the Chaos Emeralds required to fully defeat Eggman and achieve the games' "good endings" can be earned. 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); the 8-bit versions favoured a spring-filled environment (though it should be noted that the Chaos Emeralds were actually found hidden in the normal stages themselves in the first two 8-bit games); Sonic the Hedgehog 2 and Sonic 3D featured "in your face" segments with the hedgehog running along a long tunnel; Sonic 3 and Sonic & Knuckles used the same perspective but had Sonic collecting all the blue-coloured orbs on the surface of a giant sphere; and the stages found in Sonic Heroes are similar to those found in Sonic the Hedgehog 2 except that the tunnel is fully transparent and bubbles are collected instead of rings. Sonic Chaos (Sonic and Tails in Japan) featured a variety of gimmicks for its levels. However, in the later Sonic Adventure titles, the Special Stages were omitted and Chaos Emeralds were collected in non-interactive cut-scenes as part of the story.
Since the 16-bit version of Sonic 2, Sonic has had the ability to transform into the extremely fast and invulnerable Super Sonic once all seven Chaos Emeralds are collected. (Sonic 3 and Knuckles, with its greater emerald count, featured an even more powerful form known as Hyper Sonic.) 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. Again, this was changed for the Adventure series, where Emeralds were collected as part of the story and Super Sonic only appeared in the climactic final boss fights, much to the dismay of many fans, who appreciated the additional replay value offered by retrying the game's early levels with Super Sonic's additional abilities.
A few Sonic games focus on gameplay styles other than the standard side-on 2D platforming, including isometric platforming (Sonic 3D), racing (Sonic Drift, Sonic R, Sonic Riders), board gaming (Sonic Shuffle) 3D with a 3D card ("Sonic Heroes") and even educational gaming.
===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, Wave Master, 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 the upcoming Shadow the Hedgehog game. Heroes 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.