Sonic The Hedgehog

Level select

Press Up, Down, Left, Right at the title screen. A chime will confirm correct code entry. Hold A + Start to begin game play. In the Japanese version, press Up, Down(3), Left, Right at the title screen. Hold A + Start to begin game play.

All Chaos Emeralds

Enable the "Level select" code. Select the "Bonus level" option on the level selection screen. Obtain the Chaos Emerald, reset the game, and repeat the process until all of them are in your possession. Allow the game to continue after obtaining the last Chaos Emerald to start in the Green Hill Zone.

Note: When you collect all of the Emeralds, you will not become Super Sonic, but you will be practically invincible. Try the following. When you have no rings, get attacked by something. Sonic will fall back (as if he had a shield on him), but he will not die. However, Sonic will die if he falls off of the edge of something, sinks underwater, etc.

Debug mode

Press Up, C, Down, C, Left, C, Right, C, Start, then hold A at the title screen. Continue to hold A until game play begins. Screen coordinates will appear instead of a score and the number of objects displayed will appear instead of the time remaining. Use one of the following controller actions to enable the corresponding debug code. Note: This code may only be enabled on the first version of the game.

Object transformation

Press B during game play to change Sonic into a game object. Press A to change into a new object. Press C to place an object on the screen. Press B again to revert back to Sonic. Note: The type of object that may be selectable will vary from level to level.

Invincibility

Sonic is, by default, invincible in debug mode. Note: Sonic can still drown, be crushed, fall and die, etc. He is only invincible to enemy attacks.

Slow motion

Pause game play and hold B.

Restart

Pause game play and press A.

Frame advance

Pause game play and press C.