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.
Vectorman
Vectorman is a series of run and gun platform games developed by BlueSky Software and published by Sega for the Sega Mega Drive/Genesis. The first game in the series was released on October 24, 1995 in North America and on November 30, 1995 in Europe. The games have since appeared on several game compilations, including the "Sega Genesis Collection" for the PlayStation 2 and PlayStation Portable, the "Sonic Gems Collection" for the Nintendo GameCube, and "Sonic's Ultimate Genesis Collection" for Xbox 360 and PlayStation 3. "Vectorman" was added to the Wii Virtual Console on February 27, 2007, in Japan and April 5, 2007, in Europe, and in North America on September 22, 2008. It was also released on the digital distribution service Steam as part of the "SEGA Genesis Classics Pack" and as a standalone title. Vectorman was ported to iOS and Android in 2018 as part of the Sega Forever service.