Here is a list of Quake cheat codes

To use these open up the console (Hit the ~ key on your keyboard or use the menu, options, go to console to get to it) and then type the code in and hit the enter key.� Close the console (Hit the escape key).

• GOD = Toggles invincibilty on and off.
• FLY = You can fly.� Use the swim up & down keys to go up and down.
• NOCLIP = You can walk through anything.
• NOTARGET = Monsters will not attack you unless you attack them.
• GIVE S # = Gives you # number of shotgun shells.
• GIVE N # = Gives you # number of nails.
• GIVE R # = Gives you # number of rockets.
• GIVE C # = Gives you # number of cells.
• GIVE # = Gives you the # weapon.� (Example: 5 would give you the super nailgun)
• IMPULSE 9 = Gives you all weapons, full ammo, and keys.
• IMPULSE 11 = Gives you a rune.� You can only type this once each time you are in the console.
• IMPULSE 255 or IMPULSE -1 = Gives you Quad Damage.
• REGISTERED 1 = Makes game think you have registered version so you can open up barriers at start map and get lightning gun.� NOTE: Do not try to go into any slipgate episode higher than 1 unless you have the registered version!
• R_FULLBRIGHT 1 = All lighting in game is at max.
• MAP map name = Warps to map name level.� (Example: E1M1 would warp you to episode 1, map 1; END would warp you to the end of game; START would warp you to episode picker)

Try going to ID Software's web site for updates and patches on Quake.