Level select
Quickly press [X], [Up], [Right], [Up], [Right] during game play.
All weapons
Quickly press [Up], [Down], [Left], [Right], [A], [B] during game play.
God mode
Quickly press [Up], [Down], [Left], [Right], [Up], [Down], [Left], [Right] during game play.
Invisibility
Quickly press [X], [B], [A], [B] during game play.
Kung Fu fists
Quickly press [Right], [Down], [Left], [A] during game play.
Alternately, find and read the "Day of the Kungfu Zombies" books in various levels. Note: When you look at this book, it will not highlight an action response. You must search for the book then press [Action] to read it. Your character will say "I know Kung Fu?", then tattoo will appear on your hands. Your hands are now stronger, and can kill zombies.
Minigun
Quickly press [Up]x2, [Down]x2, [A], [B], [A], [B] during game play.
No knock downs
Quickly press [Up], [A], [Up], [B], [Y], [Up], [X] during game play.
Kill all spawned enemies
Quickly press [A], [B], [Y], [X], [A], [B], [Y], [X] during game play.