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 Genesis
For his part, Kalinske highlighted Sega's role in developing games for an older demographic and pioneering "the concept of the 'street date'" with the simultaneous North American and European release of "Sonic the Hedgehog 2". John Sczepaniak of "Retro Gamer" noted, "It was a system where the allure was born not only of the hardware and games, but the magazines, playground arguments, climate, and politics of the time." Sega of America's marketing campaign for the Genesis was widely emulated, influencing marketing in the subsequent generation of consoles.