god - god mode 
fly - fly mode 
impulse 9 - gives you all weapons, full ammo and keys 
no clip - walk through walls 
notarget - Guys disappear 
To play the game at Nightmare skill you need to find a hidden entrance. Walk through any of the three
entrances in the beginning where you choose skill. When you come to the room where you can choose
episode you walk through the opening to the fourth episode. Walk into the water. When you fall through
the water you back up against the wall and with a little luck you'll land on a ledge which leads to the
door where you enter the Nightmare skill. 
to make the game think its registered type registered 1. 
to warp levels type e1-4mwhat ever level for example i want to go to episode 3 level 2 I type e3m2and i warp there. 
Press ~ to bring down place to type cheats.
Type-
Impulse 9- All weapons(note: whenever you type this cheat
hit enter, then hit ~ agian to activate, then hit ~ again
to type rest of cheats)
Give r 9999999999- unlimited rockets
Give n 9999999999- unlimited nails
Give c 9999999999-  unlimited cells
give s 9999999999- unlimited shells
(note: whenever you pick up a monsters backpack, you must
enter the Give _ 999999999 codes again.)
This cheat is for those of you out there who get scared when
playing Quake. Go to the console and type in 
'NOTARGET'. All monsters will not attack you unless you
provoke them in some way (e.g you shoot them).
During playing press the ` button to bring a box 
where you can type these codes:
CD DATA = Shows the CD contents
CD EJECT =  Ejects the CD
CD INFO = More information about the CD
CD LOOP = Loop mode CD playing
CD PLAY# = Plays a desired track
CD RESET = Plays the CD from the start
CD RESUME = Resumes CD-music
CD STOP = Stops the CD-music
COLOR = You change your suit's colour
CONNECT = You try to connect to the network
RECONNECT = You retry to connect to the network
GIVE 3 = You get the double barrel shotgun
GIVE 4 = You get the nailgun
GIVE 5 = You get the perforator
GIVE 6 = You get the grenade launcher
GIVE 7 = You get the rocket launcher
GIVE 8 = You get the thunderbolt
GIVE S 255 = Ammo for shotgun
GIVE R 255 = ammo for rocket launcher
GIVE C 255 = ammo for thunderbolt
GIVE H 999 = maximum health