During gameplay press 'Tab' to display the console window and then enter the following case sensitive passwords (without the quotes) to enable the corresponding effect. Using any of the cheats though will disable the ability to save a high score for that game.
Permanent 100% Health:
Allow Use of ALL 5 Weapons:
Freeze Ducks (allows multi-kill of same duck):
Cancel Freeze Mode (see above):
Show Internal Game Info, Used for Debugging:
Unlimited Ammo for ALL Available Weapons: