Enable the console by using the option menu. Then, press ~ to display the console window. Enter seta thereisacow "1337" as a console command, then enter spdevmap bog_a as a console command to start the demo in cheat mode. Then, press ~ to display the console window again and enter one of the following codes to activate the corresponding cheat function.

Effect	Code
All weapons	give all
Enemies ignore you	notarget
Full ammunition	give ammo
God mode	god
No clipping mode	noclip
Set gravity; default is "39"	jump_height [number]
Set speed; default is "1.00"	timescale [number]