Sonic the Hedgehog
The Sega Genesis had "add-on" systems that incorporated "Sonic" games. "Sonic CD", released for the Sega CD, was a 2D platform game released in 1993. The game introduced the characters Amy Rose and Metal Sonic and featured levels that differed depending upon whether Sonic was in the past, present, or future time frames. "Knuckles' Chaotix", a spin-off released in 1995 for the Sega 32X, featured Knuckles and a new group named Chaotix fighting against Dr. Robotnik. The game featured a two-player cooperative system in which the on-screen characters were connected by magic rings. There was also "Sonic Eraser", a puzzle game released exclusively on Sega Game Toshokan in 1991.
Educational games in the Sonic series
As the "Sonic the Hedgehog" series of platform games has grown in popularity, its publisher Sega has expanded the franchise into multiple different genres. Among these are several educational video games designed to appeal to young children. The first attempt to create an educational "Sonic" game was Tiertex Design Studios' "Sonic's Edusoft" for the Master System in late 1991, which was canceled despite having been nearly finished. When Sega launched the Sega Pico in 1994, it released "Sonic the Hedgehog's Gameworld" and "Tails and the Music Maker" for it. Orion Interactive also developed the 1996 Sega PC game "Sonic's Schoolhouse", which used a 3D game engine and had an exceptionally large marketing budget. In the mid-2000s, LeapFrog Enterprises released educational "Sonic" games for its Leapster and LeapFrog Didj.