Welcome to the FX codes
 
Blue codes are old, they can be found everywhere or in a few places.
 
Red codes I've found in mags and sites but I can't get them to work. (they are probably fake)
 
Green codes- I don't have this game so I can't test it.
 
Orange codes are discovered by me, you might find them elsewhere but they were here first.
GAME GEAR
Sonic Labyrinth
Required to beat game
Level 2-3 hold Right+1+2 when shot from cannon
 
Level 4-2 beat level fast (chimes and birds fly out of a clock if done fast enough)
 
Codes
 
Level Select - At title screen press Up, Up, Right, Right, Right, Down, Down, Down, Down, Down, Down, Left, Left, Left, Left, Left, Left, Left, Left, Left