Level select -
At the main menu, hold [Alt] + [Ctrl] to display the level selection screen.

Suicide missions -
At the main menu, hold [Alt] + M.

Cheat Codes -
While playing a game, hold [Ctrl] and type one of the following codes to 
activate the corresponding cheat function. If you entered the code correctly, 
you will hear the sound of breaking glass.

Result - Cheat Code
God mode - atheist 
Mission objectives complete - qed 
Mission skip - soia 
All access cards - axes 
All grenades - horse 
All squad members have all weapons - thrill 
All weapons, ammo, and full heath - aslag 
Alternate field view - phish 
Area extraction zone - ext 
Berserk squad members - hdcs 
Enemy (green) and items (white) on map - godeye 
Flame-thrower - tozt 
Freezes opponents - klatu 
Full armor - arm 
Full health for squad members - phnx 
Full heath - hell 
Full oxygen - oxy 
Infrared vision - acid 
Kill squad member 1 - ksa 
Kill squad member 2 - ksb 
Kill squad member 3 - ksc 
Kill squad member 4 - ksd 
Locations displayed on map - blue 
M-16 and ammo - xse 
MP5N machine gun and ammo - vent 
Rocket gun and ammo - deth 
Squad member revolt - nimrod 
Squad members have full heath - medic 
Squad members talk - chat 
Super jump - asd 
Two pistols and ammo - woo 
Two shot guns and ammo - freedom 
170 degree field view - vomit