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.
Sega Saturn
Released in 1988, the Genesis (known as the Mega Drive in Europe, Japan and Australia) was Sega's entry into the fourth generation of video game consoles. In mid-1990, Sega CEO Hayao Nakayama hired Tom Kalinske as president and CEO of Sega of America. Kalinske developed a four-point plan for sales of the Genesis: lower the price of the console, create a U.S.-based team to develop games targeted at the American market, continue aggressive advertising campaigns, and sell "Sonic the Hedgehog" with the console. The Japanese board of directors initially disapproved of the plan, but all four points were approved by Nakayama, who told Kalinske, "I hired you to make the decisions for Europe and the Americas, so go ahead and do it." Magazines praised "Sonic" as one of the greatest games ever made, and Sega's console finally took off as customers who had been waiting for the Super Nintendo Entertainment System (SNES) decided to purchase a Genesis instead. However, the release of a CD-based add-on for the Genesis, the Sega CD (known as Mega-CD outside of North America), was commercially disappointing.