Sonic the Hedgehog CD Cheats and Tips
The Master Code
From the title screen, press Down, Down, Down, Left, Right, A (or Space) to call up a Sound Test menu. Special things will happen if you select the following sound combinations and press Start:

FM40, PCM12, DA11 - Construction/ Debugging Mode
FM07, PCM07, DA07 - Play All The Special Stages
FM42, PCM03, DA01 - Displays artwork
FM46, PCM12, DA25 - More artwork
FM42, PCM04, DA21 - Sonic Hercules
FM44, PCM11, DA09 - Revenge of the Mutant Artwork

Level Select
At the title screen, press Up, Down, Down, Left, Right, B (or Space).

Note: This code only lets you play one level. You will be sent back to the title screen upon completion or if you time warp.

Beat the Clock
First, finish the game successfully. Now play Time Attack and beat the following times for some special options:

37'
If you beat this time you can play the bonus stages in Time Attack. To access these stages, press Left in the Time Attack screen.

30'
Beating this time adds a new item to the main menu. To the left of RAM Data there will be an entry titled D.A. Garden. It's a picture of the little planet. With the controller you can rotate the planet (with B), zoom in and out (with C), and listen to all the music in the game (with A). It allows you to listen to the regular music, a good mix, and a bad mix, for each level.

25'
Finally, if you can beat this time another menu item appears. To the left of D.A. Garden you'll find Visual Mode. This option allows you to watch the introduction, the endings, and a pencil test of Sonic running around. It also has a cool picture of Sonic in the background.

Tip: To beat these times easily, enable Debug Mode as described under Cheat Codes and Sound Test. This will disable the clock so you'll always finish in 0 seconds!

Designer's High Scores
To see the high scores of the game designers, press Right, Right, Up, Up, Down, C.

I'm Outa Here!
If you let Sonic sit for three minutes without doing anything, he'll grow bored, say "I'm outa here!" and race off the screen, thus ending the game.

Quick Death
While playing, pause the game and press A, B, or C. This can be useful if you find yourself trapped.

The Secret Special Stage
Enter the Sound Test screen, and enter 7's in all the boxes. When you play that sound a secret stage will appear.