Invincibility
On the pause menu, press: R, Left, L, Right, Up , Select, Left. You should hear a voice confirmation.
Unlock All Levels
On the pause menu, press: R, left, L, right, up, select, R. You should hear a voice confirmation.
Instant 500 Bullets
On the pause menu, press: R, Left, L, Right, Up, Select, Right. You should hear a voice confirmation.
Higher Pitched Voices
On the pause menu, press: R , Left, L, Right, Up, Select, L. You should hear a voice confirmation.