Enter these at the console. To get the console, right-click on
sof.exe in your demo directory and choose "Create shortcut" and
then right-click on the shortcut you've created and choose
"Properties". Change the command line to add this:
+set console 1

It should look something like this when finished:
"c:\....\SOF\sof.exe" +set console 1

Bring up the console by pressing "~":

Code Result
heretic - God Mode
phantom - Walk Through Walls
ninja - Enemies Don't See You
elbow - Give Weapons 1-5
bigelbow - Give Weapons 6-10
matrix # - Timescale (replace # with 1-10)
gimme X - Spawn Object/Item X
updateinvfinal - Gives More Ammo
killallmonsters - Kills All Enemies