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 the Hedgehog (1991 video game)
Sega of America CEO Tom Kalinske wanted reassurance that the character would not fail. The global head of marketing, Al Nilsen, became involved, and playtested the game across the United States with Mario fans: they were shown "Mario" and then played "Sonic the Hedgehog". 80 percent preferred "Sonic the Hedgehog", and the game was shown at the 1991 Summer Consumer Electronics Show. It was released in North America on June 23, 1991, and in the PAL regions and Japan the following month. Sega of America packaged it with American Genesis consoles, replacing "Altered Beast". This tactic enabled Sega of America to sell 15 million Genesis units. Genesis owners who bought their consoles before the switch could request free copies of "Sonic the Hedgehog" by mail. Sega of America created a large-scale marketing campaign, promoting Sonic as its mascot.