Cheats Codes:
To enable cheat codes is necessary to type letters on the keyboard during the game. If you use the cheats while in Gun Mode, the effects will not show up until you begin Campaign Mode by using the "Complete Level" cheat.
Code - Result:
cheate - Level Skip
cheath - Add Health
cheatw - All Weapons
cheata - Add Ammo
cheatm - Add Credits (Enter at Shop Screen)