Type in the following while playing the game:

Code - Effect

ioigod - god mode
ioiflymo - ragdolls
ioicharisma - max charisma
ioiammo - infinite ammo
ioiblind - invisibility
ioifastmo - fast motion
ioislowmo - slow motion
ioishotgun - shotgun
ioirocket - rocket launcher
ioisniper - sniper rifle