Any game that kills you with a single measly bullet is asking to be sabotaged, so let's oblige. Bring up the chat window by pressing the apostrophe key and type in these Clancy clouting codes:
Teamgod All team members are invulnerable
Avatargod Player god mode; only the player you control is invulnerable
Stumpy Stumpy mode: change characters' appearance - to say the least
Clodhopper Enlarge characters' hands and feet
Bignoggin Big-head mode
Meganoggin Mega big-head mode
5fingerdiscount Replenish ammo
Nobrainer Toggle AI on/off (you can't move through doors, stairs or ladders with this code in effect)
Debugkeys Debug enabled or disabled keys
Silentbutdeadly Move around after typing in the code or you'll miss the joke
Turnpunchkick 2D character mode - most peculiar
1-900 Perverted heavy breathing mode
Explore Turn the mission's victory conditions on/off; perfect on Operation Yellow Knife because it lets you kill the terrorists and Anne Lang