To cancel invulnerability enter the weapon selection screen. Press Circle + R1.
To disable no collisions switch to jetpack mode and press Triangle to display the weapon select screen. Press L1 + Right + Down.
Highlight a game from the load game menu. Press L1 + L2 + R1 + R2. Exit the load game menu. Levels with the Butthead monster will be modified by the code.
To get full ammo do a back flip by pressing Square + L2. Press Right + X + Circle while in the air. The ammunition for all weapons will be returned to full.
To get full health do a back flip by pressing Square + L2. Press Down + X + R2 while in the air. Ox's health will be returned to full.
To get full inventory press Square + Select to enter 3D map mode. Press Left until the map arrow points toward you, then press Start to return to standard map view. Press L1 + Square + X + Circle while the camera is rotating. Press Select to exit Map mode.
To unlock invincibility use the full inventory code or find the drill to place it in inventory. Use the frying pan as the current weapon. Enter the weapon selection screen and highlight the drill, then press Circle + R1. The flashing number "999" next to the health meter confirms correct code entry.
At the main menu press and release L1 + L2 + R1 + R2 + Up. Press Circle to start a new game. From the difficulty menu, press L1 + L2 + R1 + R2 + Down. Choose a difficulty and the level select menu will appear.
To have no collisions switch to jetpack mode and kill an alien. Stand on the alien and press Triangle to display the weapon select screen. Press L1 + Right + Down. Ox will be able to fly through the walls and move anywhere in the level.
To view the ending save at least one game. Go to the main menu and highlight "Load Game". Hold Right, then press Circle. Release Right and press Triangle to cancel. Next, press Left + Square, then press Triangle to cancel again. The ending sequence will be displayed.