Press [Talk] during game play. The game will freeze. Enter one of the following codes, then press [Enter] to activate the corresponding cheat function:

notarget - Invisibility
god - Invulnerability
ammo - Full ammo
armor - Full armor
health - Full health
guns - Get all weapons
kfa - Get all weapons, full ammo, armor & health
tears - Get all weapons, infinite ammo
gear - Increased health and boosted reflexes
gimmegun pistol - Get pistol
gimmegun dual pistols - Get dual pistols
gimmegun submachinegun - Get SMG
gimmegun shotgun - Get shotgun
gimmegun assault rifle - Get assault rifle
gimmegun semi-auto rifle - Get semi-auto rifle
gimmegun nail gun - Get nailgun
gimmegun cannon - Get cannon
gimmegun plasma weapon - Get plasma railgun
gimmegun missile launcher - Get missile launcher
gimmegun frag grenade - Get frag grenade
gimmegun proximity - Get trip bomb
gimmegun remote charge - Get pipe bomb
gimmegun turret - Get turret
poltergeist - Ghost mode
maphole - Next level
build - Show build version
pos - Show player position