Sonic CD Cheats

Press Down, Down, Down, Left, Right, [Space] at the title screen to enable the sound test screen and chat mode. Enter and play one of the corresponding sound combinations to activate the corresponding cheat function:

PCM12, DA11 - Debug mode
PCM07, DA07 - Bonus levels
PCM03, DA01 - Display artwork
PCM12, DA25 - Human-faced Sonic
PCM04, DA21 - Hercules Sonic
PCM11, DA09 - "Revenge of the Mutant Artwork"

Level select
Press Up, Down, Down, Left, Right, [Space] at the title screen. You can choose any past, present, or future level to play. However, when you warp or finish the level you will return to the title screen.

Development team high scores
Press Right, Right, Up, Up, Down, [Space] at the title screen.

Rewards for Time Attack mode
Having your total record in Time Attack mode under certain times will unlock special features.

D.A. Garden: Beat Time Attack mode in under 37'27''57
Sound Test: Have your total record be under four minutes.
Special Stages in Time Attack: Beat Time Attack mode in under 30'21''05
Stage Select: Have your total record be under five minutes.
Visual Mode: Beat Time Attack mode in under 25'46''12