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
Journalists and fans have speculated about the impact a completed "X-treme" might have had on the market. David Houghton of GamesRadar described the prospect of "a good 3D "Sonic" game" on the Saturn as "a 'What if...' situation on a par with the dinosaurs not becoming extinct." IGN's Tavis Fahs called "X-treme" "the turning point not only for Sega's mascot and their 32-bit console, but for the entire company", but noted that the game served as "an empty vessel for Sega's ambitions and the hopes of their fans". Dave Zdyrko, who operated a prominent Saturn fan website during the system's lifespan, said: "I don't know if ["X-treme"] could've saved the Saturn, but ... "Sonic" helped make the Genesis and it made absolutely no sense why there wasn't a great new "Sonic" title ready at or near the launch of the [Saturn]". In a 2007 retrospective, producer Mike Wallis maintained that "X-treme" "definitely would have been competitive" with Nintendo's "Super Mario 64". By contrast, "Next Generation" reported in late 1996 that the game did not compare well to contemporary competition, and would have harmed Sega's reputation if it had been completed and released. Naka stated that he was relieved by the cancellation, as the game "wasn't looking very good from my perspective".