TOTAL ECLIPSE 3D0
At the options/start screen highlight the quit/previews menu. press and hold the X button and tap the B, L then A Let go of the X button, Then press B,L,A two more times then a level select screen will appear.
*GET 99 LIVES
Begin a game then pause and enter the options screen. Rotate to resume game over the picture in the right. press B,A,C,A,B,A,L and press L and R simultaneously, then X,X. A skull will materialise then press start and a larger skull will appear then press A,A,B,B,C,C,L,L,R,R,start. Go back to the game and you will have 99 lives.
source 3d0 magazine