Use a text editor to edit the "bia.ini" file in the "system" folder in the game directory. Look for the "[Engine.GameInfo]" heading, then enter the line "bCheatsEnabled=True" below it. Then, look for the "[Engine.Console]" heading and change the "ConsoleKey=0" line to "ConsoleKey=192". Then, press ~ during game play to display the console window:

Extra ammunition - allammo
Togle invisibility - invisible
Kils everything - killall
Get all items - loaded
Remove all items - unloaded
God mode - god
Flight mode - fly
Disable flight and no clipping mode - walk
All weapons - allweapons
No clipping Mode - ghost
Select map - loadspmap
Old movie mode - oldmovie
Spawn indicated item - summon
Toggle blind AI - blindai
Toggle deaf AI - deafai
Toggle blind enemies - blindenemies
Toggle deaf enemies - deafenemies
Unknown - soundocclusion
Unknown - smiteevil
Unknown - avatar
Unknown - supersquad
Unknown - lightperiod
Unknown - lightcone
Unknown - pawnanimextra

Successfully complete the game under the normal difficulty setting. This cheat must be enabled again if the player is killed, retires, or starts a new level.

Successfully complete the game under the easy difficulty setting. This mode allows the game to be played in black and white.