Cheat codes
During the game press Esc to get to the main menu and type 'DOUGMATIC' several times until you're taken back into the game. You're now in cheat mode. Press Esc and type the following:

Protectme	God mode
Loadme	Unlimited ammo
Giveme	All weapons
Arctic	Arctic level
Healme	Full health
Hq	Headquarters
Killem	Kill villains
Moveme	Saved games of all levels
Agentj	Agent J
Agentk	Agent K
Agentl	Agent L
Agentx	Agent X