The following codes are for SINGLE PLAYER ONLY. Press ` to bring 
down the console, then type:

Code            Result 
iamtheone -  Activate Cheat Mode 
fly -   Fly Mode 
god -  God Mode 
loaded -   All Weapons 
allammo -  All Ammo 
ghost Walk -   Through Walls 
walk  -    Walk Mode 
killall [class]  -    Kills All Enemies of a Certain [class] 
playersonly -    Freezes Time, Type Again to UnFreeze 
behindview 1 -    View Character from Behind 
behindview 0 -     Normal View 
open [mapname]  -   Jump to Any Map