Start game as usual - go to the BRIEFING SCREEN (where you can select "START MISSION" and "BUY STUFF") and press the TAB key to bring up the cheat codes menu and enter following codes using the CURSOR KEYS (e.g. RDRL = RIGHT, DOWN, RIGHT, LEFT).
ESC closes the cheat menu when youre done.
LULRD - All Movies Unlocked
RDRL - Get all Weapons
RLLDU - Add +50000 Arconium
RULRU - Unlock All Levels
RDRDR - Unlimited Shields
UDDRDU - Unlimited Secondary Ammo