Console codes
During the game, hit L to bring down the console. 
Now type /tell cheatcheat. You can now enter any of the following codes.

Result - Code 
Enemies invincible - /tell hitlermode  
Enemy camera - /tell ec  
Enemy field of view - /tell fovs  
Flight mode - /tell fly  
Get item  - /tell give: (0-44)  
God mode - /tell godmode  
God mode + unlimited ammo, flight - /tell ac  
Invisibility - /tell invis  
Lose mission - /tell losemission  
Render arrival points - /tell arrival  
Render astar paths - /tell astar  
Render cover nodes - /tell cvdraw  
Render patrol paths - /tell pathdraw  
Render waypoint - /tell wpdraw  
Render waypoint connections - /tell wpcondraw  
Thompson M1 - /tell give  
Toggle HUD - /tell noint  
Unlimited ammo - /tell ammo 
View game stats - /tell stats  
Win mission - /tell winmission