Cheat codes:
Press the ` key to bring up console, then enter the cheats.
Cheat.GodMode() = Godmode
Cheat.AddAmmo() = 500 Ammo
Cheat.FullHealth()= 100% Health
Cheat.GiveAllWeapons() = Give All Weapons
Cheat.GiveAllAmmo() = Give All Ammo
Cheat.NextMission() = Advance to next mission
(supplied by: scania1, KingDaniel)