Sonic the Hedgehog CD, a classic Sega CD title, is a platform game featuring Sonic the Hedgehog. It's a side-scrolling adventure characterized by its innovative use of the Sega CD's capabilities, notably its enhanced sound and CD-quality music.  Gameplay involves navigating levels, collecting rings, and defeating enemies, with time travel mechanics added to the core gameplay loop. Several prototypes existed before the final release, highlighting the game's development journey.  Sonic Team, a division of Sega, developed and released this iconic game.

Sonic the Hedgehog CD (Dec 4, 1992 prototype)

Sonic Megamix 5.0