hit the console key"~" and the following
Code: Effect:
god God mode
give all All weapons
devmap [map name] Change maps
mapname List maps
noclip No clipping mode
notarget Disable AI

That doesn't really help, and the cheats only work on MAK!!!

Console commands you can use in co-op and single player without booting the "devmap"
first:
sf_use_bw 1 = Black and White movie mode
sf_use_ignoreammo 1 = Infinite ammo
sf_use_invert 1 = Photo negative mode
sf_use_chaplin 1 = Silent movie mode

To boot a developers map and use all cheats:
devmap [map name] = starts the selected map in developer mode and you can use god mode and
all cheats.

Cheat modes that I know require the devmap command to be booted first:
god - God mode
demigod - Double health

Console commands that may or may not require that you be in a devmap to use. I haven't
tried them except in devmap mode:
notarget - Disable AI
mapname - List maps
give all - All weapons
noclip - No clipping mode

For those that don't know:

No Clipping means that you can walk through walls and certain barriers. It has nothing to
do with ammo clips or reloading*.

I don't know if it will allow you to walk outside on a zombie map or not, I haven't tried
it yet.
For all I know, it may allow the zombies to walk through the barriers also, so I would try
it out on a lower level.

*Use the unlimited ammo command for unlimited ammo and no reloading.

TAKE A HUGE **** IN YOUR MOMS MOUTH!!!!!!!!!!!!!!!!!!!!!!!!!!

were do u tipe in theas in is in game

when do i type this stuf in? i pressed the ` button and nothing happened. i typed all the
codes, but it didnt work :(

you have to enable console