At the Sonic The Hedgehog title screen, press Up, Down, Left, Right. Hold B for level select and sound test.
Sonic The Hedgehog - Debug mode
At the Sonic The Hedgehog title screen, press Up, X, Down, X, Left, X, Right, Up, X, Down, X, Left, X, Right, X, Now hold B and press Start. Press A to enter debug mode.
Sonic and Knuckles - Level select
Start a game with Sonic and run over to the Madmole near the Super Shoes power-up. Directly to the right of the Madmole is a pulley mechanism that takes you to the next level above by pushing Down on it. Instead of pushing down, push the Left, Left, Left, Right, Right, Right, Up, Up, Up. Now press Start to pause the game and press B. You will be sent back to the main screen. When you can select between Sonic and Knuckles, hold B and press Start for a level select.
Sonic 3 - Pick Level
As you hear Sega spoken but BEFORE the main menu appears press: Up, Up, Down, Up, Up, Up. Then at the title screen press Up to get Stage select and Sound Test.
Sonic 3 - Get Extra Stage
After doing the Pick Level code/cheat, go to the Sound test screen and play sounds 01, 03, 05, 07. Now highlight Special Stage 2 and hold B and press START.
Sonic 2 - Be Super Sonic
After you've done the Pick Level code/cheat go to the Sound test screen and play sounds 04, 01, 02, 06. Now collect 50 rings and jump to be Super Sonic.
Sonic 1 Pick Level & Sound Test
First go to the Sonic 1 title screen and press Up, Down, Left, Right. Now hold B to pick a level & get sound test.
Sonic 1 Debug Mode
First go to the Sonic 1 title screen and press Up, X, Down, X, Left, X, Right, Up, X, Down, X, Left, X, Right, X. Now HOLD B and press Start. Now when the game starts press A to go to debug mode.
Sonic 2 Pick Level
First go to the Sonic 2 Sound Test screen and play sounds 19, 65, 09, 17. Now hold X and press START. Now on the title screen hold B and press START.
Sonic 2 Debug Mode
First go to the Sonic 2 Sound Test screen and play sounds 01, 09, 09, 02, 01, 01, 02, 04. Now at the sound test screen hold B and pick a level and Start.
Sonic 3 - Debug Mode
Go to the Stage Select screen and hold button B. Then pick a level and start.
