By traveling through time, players can access different versions of stages, featuring alternative layouts, music, and graphics. Sonic CD introduces time travel as a game mechanic. Like other Sonic games, Sonic runs through themed levels while collecting rings and defeating robots. As Sonic the Hedgehog, the player attempts to protect an extraterrestrial body, Little Planet, from Doctor Robotnik.

Sonic the Hedgehog CD is a 1993 platform game developed and published by Sega for the Sega CD.