1993 (Sega/Mega-CD), 1996 (PC)
Sonic CD was released in 1993. As its name implies, one must have the Sega/Mega-CD peripheral for the Genesis/Mega Drive in order to play. This enabled a wider range of colours and CD-quality music. The game was rereleased in 1996 for PCs.
American (Sega CD)
A demonstration version of the game premiered at a event known as Yuusei Sega World. The title screen has a few noticeable differences including a larger gold Sega logo below which is the copyright date in the same gold effect with the copyright symbol splitting the year in half. The menu is located above the logo which itself reads CD Sonic the Hedgehog, the earlier name for the game. Below right is a credit for the Japanese/European opening theme song for Utoku (Mi-Ke). Upon completion of the few levels accessible in the game, a large distinctive 'Comin' Soon' screen will scroll slowly across the screen. Interestingly, this screen is accessible from the sound test in the final/released game.