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.
Sonic Spinball
Morawiec believed that the game would face "acceptance challenges" from both fans and the gaming media, as "Sonic the Hedgehog Pinball" strayed away from the traditional platforming genre. After returning home to the United States from Europe, Morawiec was surprised to find that the game had sold well, and was pleased that it benefited from the franchise's popularity. Nonetheless, he regretted that the team had lacked time to "polish" the game properly. After the Game Gear title "Sonic Drift" received poor reviews in Japan, Sega released an 8-bit port of "Sonic Spinball" for the Game Gear in its place worldwide in late 1994. It was also released for the Master System in Brazil and Europe in 1995. The 8-bit version is mostly identical to the Genesis game, albeit with downgraded visuals and different, more platforming-oriented bonus stages. The Master System version was released near the end of the console's lifetime and did not sell well, and became a valuable collector's item.