Quake 64
Walk Through Walls
Enter NOCLIP at the password screen. This enables players to walk through walls.

 Walk Through Walls
 Debug Mode
Quake Debug Mode(all cheats)
In the password screen type QQQQ QQQQ QQQQ QQQQ until it says "incorrect password" , then go to the options screen and on top will be "DEBUG". Debug mode includes: Warp to levels, weapons on, god mode on, and targets.
Credit Goes To: IGN 64