Cheat Mode:

In game just press 'T' and then enter the following codes:

Code Result

mpimyourfather - God Mode
mpwegotdeathstar - Infinite Ammo
mpkingoftehmonstars - All Items/Weapons & Unlimited Ammo
mpmaphole - Complete Mission
mpdrdentz - Full Health
mpwonderbra - Full Armor
mpyoulooklikeyouneedamonkey - Add All Armor Options
mpgoattech - All Weapon Upgrades
mpmiked - Exit Game
mpbuild - Show Game Build
mpasscam - 3rd Person View
mprosebud or mpracerboy - Spawn Snowtruck
mppos Toggle - Position Display
mpflowerpower - Paintball Mode
mpexorbitantamounts - More Blood Mode
mppos Position - Toggle Display
mpkingofthemonsters or mpmimimi - All Weapons

Hints:

Even though they may seem redundant, the training missions will get you up to speed on using all your weapons and gadgets.

Be very careful when trying to complete a stealth mission; even brandishing your weapon can blow your cover.

Silencers and quiet weapons are very helpful. There's nothing worse than making a racket and having to deal with an onslaught of enemies.

If your weapon has a scope, always use the zoom feature you will be able to take out targets with far more accuracy.