These codes are for the Genesis version only. Some codes require locking on different Sonic game cartridges onto the Sonic & Knuckles cartridge.
Level select[edit]
On Mushroom Hill grab on one of the elevators and press 
. Go back to the title screen and hold 
and 
.
Debug Mode[edit]
On a vine in Angel Island Zone, input the level select code above and you'll hear a chime. Press , then press . Back at the title screen, enter Sound Test and go to the Mushroom Hill Zone and enter the level select code again on one of the machines. Once again, you should hear a chime if you input it correctly. Press and again to go back to the title screen, but don't let go of . Now you can select a zone while holding down . Keep the button pressed until the name of the zone disappears. Use 
to toggle between debug mode being on or off.
- In debug mode
: Change sprites
: Add sprites
- In normal mode
- : Reverse gravity
- : Jump