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.
Home video game console
To compete with emerging next gen consoles, Nintendo released Donkey Kong Country which could display a wide range of tones (something common in fifth-generation games) by limiting the number of hues onscreen, and Star Fox which used an extra chip inside of the cartridge to display polygon graphics. Sega followed suit, releasing Vectorman and Virtua Racing (the latter of which used the Sega Virtua Processor). Sega also released the 32X, an add-on for the Genesis, while their Sega Saturn was still in development, and announced that they would replace the Genesis with the Neptune, a combination 32X and Genesis, and sell it as a budget console alongside their upcoming Saturn. Despite public statements from Sega claiming that they would continue to support the Genesis/32X throughout the next generation, Sega Enterprises quietly killed the Neptune project and forced Sega of America to abandon the 32X. The 32X's brief and confusing existence damaged public perception of the coming Saturn and Sega as a whole.