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.
List of Sega CD games
The Sega CD, originally released as the in most regions outside of North America and Brazil, is an add-on device for the Sega Genesis video game console, designed and produced by Sega. It was released in Japan in 1991, North America in 1992 and in PAL regions in 1993. The device adds a CD-ROM drive to the console, allowing the user to play CD-based games and providing additional hardware functionality. It can also play audio CDs and CD+G discs. While the add-on did contain a faster central processing unit than the Genesis, as well as some enhanced graphics capabilities, the main focus of the device was to expand the size of games. Known for several games such as "Sonic CD" and for the controversy of violent video games including "Night Trap", the Sega CD sold 2.24 million units worldwide. It was officially discontinued in 1996.