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 v. Accolade
As a result of the piracy and unlicensed development issues, Sega incorporated a technical protection mechanism into a new edition of the Genesis released in 1990, referred to as the Genesis III. This new variation of the Genesis included code known as the Trademark Security System (TMSS), which, when a game cartridge was inserted into the console, would check for the presence of the string "SEGA" at a particular point in the memory contained in the cartridge. If and only if the string was present, the console would run the game, and would briefly display the message: "PRODUCED BY OR UNDER LICENSE FROM SEGA ENTERPRISES LTD." This system had a twofold effect: it added extra protection against unlicensed developers and software piracy, and it forced the Sega trademark to display when the game was powered up, making a lawsuit for trademark infringement possible if unlicensed software were to be developed. Accolade learned of this development at the Winter Consumer Electronics Show in January 1991, at which Sega showed the new Genesis III and demonstrated it screening and rejecting an "Ishido" game cartridge. With more games planned for the following year, Accolade successfully identified the TMSS file. They later added this file to the games "HardBall!", "Star Control", "Mike Ditka Power Football", and "Turrican".