Sonic the Hedgehog
Due to the success of "Sonic" games on the Sega Genesis, the series was introduced to the Master System and the Game Gear. Sega began by releasing "Sonic the Hedgehog", a 2D platform game, in 1991. The game featured Sonic's ability to run and to jump at high speeds like its Mega Drive/Genesis counterpart but with notably different level design and music. Sega later released "Sonic the Hedgehog 2" another 2D platform game, in 1992. The game differed from its Genesis counterpart with different levels and music and by not including a "spin dash" maneuver. It also featured a different storyline in which Doctor Robotnik kidnaps Tails, who is non-playable in the Master System/Game Gear version. "Sonic Chaos"/"Sonic and Tails" (Japan), released in 1993, was similar to the earlier two Sega Master System/Game Gear "Sonic" games, but featured Tails as a playable character. A sequel, "Sonic Triple Trouble"/"Sonic and Tails 2" (Japan), a 2D platform game, was released in 1994 for the Game Gear and introduced a new character, Nack the Weasel, who, along with Knuckles and Doctor Robotnik, raced to collect the Chaos Emeralds. One of the last games for the Sega Game Gear, "Sonic Blast", was released in 1996 and featured prerendered sprites.
Sonic Mega Collection
"Mega Collection" was developed by Sonic Team, the studio behind most games in the "Sonic" series. According to director Yojiro Ogawa, Sonic Team's goal with the compilation was to introduce children to older games in the series and showcase what made "Sonic" successful. Sonic Team chose to focus on including all the Genesis "Sonic" games. Rather than porting them from the Genesis, they collaborated with VR-1 Japan to develop an emulator to run the games' ROM images. Series co-creator Yuji Naka, who served as producer, said the team intended to include the 1993 Sega CD game "Sonic CD", but storage constraints prevented this. Sonic Team also considered including BlueSky Software's "Vectorman" (1995), and "Sonic R" (1997) and "Sonic Shuffle" (2000) were expected to appear in "Mega Collection" at one point. "CD", "Vectorman", and "R" later appeared in "Sonic Gems Collection" (2005), a successor to "Mega Collection" focusing on rare "Sonic" games. Sonic Team had trouble gathering materials for the compilation because it had been a decade since they made the games and "Sega's not that good about keeping history." For instance, Naka wanted to include the original prototype of the first game but Sonic Team could not find its ROM image.