Primary Collection of Cheats
Cheat Mode
To enter the ''command line'' press the [~] key at any time during gameplay. Enter the following into the lines and press Enter to enable cheats.
god - Enables God Mode (invincibility)
fly - Enables Fly Mode
kill - Instant death
give S# - Gain # shells
give H# - Gain # health
give N# - Gain # nails
give R# - Gain # rockets
give C# - Gain # cells
give # - Get weapon #
noclip - Walk through walls. Repeat to turn off.
notarget - Monsters won't attack you unless provoked.
impulse 9 - All Weapons.
impulse 11 - Display runes (you don't actually get them)
impulse 13 - Silver key.
impulse 14 - Gold key.
impulse 255 Quad Damage.
map ExMy - Warp to episode X, mission Y
skill # - Sets difficulty level (# = 0-3)
sv_gravity -# - Reduces gravity by #%.
Another Set of Cheats for This Game
Crypt of Decay mode
This is even harder than the hidden Nightmare skill. To reach it, follow the instructions for the Nightmare difficulty, but when you start down the hallway to the portal before you turn, there will be a wall decoration type thing. Shoot this with your shotgun, you will know if you did it because the wall will bleed and a message saying you have selected Crypt of Decay mode pops up. Then proceed down the hallway to the portal and choose your episode.
Feign Death
This is pretty strange and I can't really figure out if it is a secret or a bug but here it is. Type in "Give health". You die but you are still alive. It looks like you are dead and bad guys can not see you but you can shoot. If your health goes down the slightest you are really dead but until then you aren't. To move, you put god mode on and get your rocket launcher out. Shoot the wall and it will richochet in your favored direction.
Hidden Picture: The Crypt of Decay
To find the "Dopefish," when you see the exit, turn back go onto the bridge. You should see a quad power-up on a ledge. When you get on the ledge, you will see an extremly small ledge that you can barely walk on. At the end, you can jump into "The Well of Wishes." The Dopefish will be there.
Hidden Picture: The Underearth
To find the weird picture, find all the faces on the walls and shoot each once. You will know which ones you shot because blood will come out only the first time. When you shoot all of them, look for a hallway with a short opening and a villain on each side. One of them will open to a small room with a picture in it.
Nightmare Mode
Go to the episode 4 entrance and enter the water. Now backup against the wall as if trying to go back the other way. Stay there until you fall again. You should land on a big piece of wood. Walk along the side to find another entrance that leads to the Nightmare gate.
Power Up Cheat (with Armor)
This code has been tested with version 1.06. Beat any episode of Quake and save as much ammo and armor as possible. After you return to the level select screen, save your game and quit out of the game entirely. Now re-enter the game and open that save file. Walk backwards into the teleporter and return to the first telepad (where you start the game.) Go toward the Hard difficultly and fall into the lava. When you restart, you will respawn with all your health, ammo, armor and weapons! You will lose your rune but that's alright compared to the power you have to enter later episodes.
Secret Level
To find The Underearth level you must be in The Crypt of Decay. When you see the exit, go straight back. You should be in a room with boxes and a button on the ceiling. Shoot the button, then jump on the boxes into the secret room. Push the button, then go to the hidden "Well of Wishes." Now look around the walls and a wall will open for you. When you get out, there will be a underwater doorway that leads to the secret level.
Ziggurat Vertigo
In episode 1 at "The Grizzly Grotto", after you hit all quake switches after going up the elevator, doors will open to your left and right. Enter one and hit the switch. Do the same thing again on the other side. It will say "A secret cave has been opened." Go to the water. when you enter, look around. You will see a cave opened where a portal leads you to Ziggurat Vertigo.
Beat Shub-Niggurath
When you enter the room with Shub-Niggurath you'll see a spiked ball if you play through the level. When it goes through Shub-Niggurath, walk through the teleporter on the walkway.