You need to start the game with a command line parameter:

for version 1.0 type: wolf3d -next

for version 1.1 type: wolf3d -goobers

Once in the game, you need to activate the cheats:

for version 1.0 press CTRL + ALT + ENTER

for version 1.1 press LSHIFT + ALT + BSPACE

Now you can use these cheat codes:

Code Description
TAB + G God Mode
TAB + I Add Item
TAB + H Self-Mutilation
TAB + N No Clipping Mode
TAB + P Pauses Game
TAB + Q Exits
TAB + W Turbo mode
TAB + X Adds Extra Stuf
TAB + E Finishes Level
M + L + I Weapons, ammo and invulnerable