Enter these at title screen / after loading file

openallchars - unlocks all hidden characters
lockchars - locks the characters back up
phshowalllevels1 - opens all levels
openpanda - unlocks panda character
openwannabe - unlocks wannabe character
openpredator - unlocks the Kao character


Enter these in-game

iddqd - kill all (includes you )
iddqdboss - same as kill all, but for bosses
call terminator - either cancels a call to the police, or summons Arnold. Your guess is probbaly correct.

Call UFO - i have no idea what this does

the rest aren't needed, so don't mess with em.



And don't be a jerk abotu using them! Keep discussions about them here, and don't ask about them in the regualr discussions page for the game.
cheers!