From Wikipedia Sonic the Hedgehog 2 is a side-scrolling platform video game developed by Aspect Co., Ltd. and released by Sega for their Master System and Game Gear formats. Though based on the original game of the same name, it is a distinct game, with different level designs and a different plot, and this version, unlike the 16-bit release, does not have the spin dash, which led it to being thought to be made before the Sega Genesis version.