"As I was playing a 12 player deathmatch in Ziggurat Vertigo, I had an idea. As we were playing, someone would keep going to the dedicated console and changing the gravity. It got to a point when you might jump, float, get pulled to the roof (- gravity), and then rocket towards the ground. Not knowing what the gravity was about to do was kinda fun.
PS. Try making SV_FRICTION negative. It's hard to control - you accelerate instead of stopping."
Also, when in the level choice area (not the difficulty choice area) go to the console and do a NOCLIP. Use the "D" and "C" keys to go up/down. Through the floor you will find the stairs leading to the entrance to the final level (Shub-Niggurath's Pit). As before, the game hangs if you do try to enter the level itself.
An alternative method of viewing the entrance to Shub-Niggurath's Pit is given in the Secrets section, under level E1M7 (The House of Chthon).
Go to Multiplayer and select New Game. You will of course be on your own (no monsters, no other players). Now call up the Single Player menu and load a saved (single-player) game. All the grunts will look like Quad Damage, all the dogs will look like boxes of NIN, and so on. The level itself may also look "like a level that hasn't had its nodes rebuilt" (if you understand DOOM terminology) and may fail completely after a while, with a screenful of error messages.
Thanks to a bug in version 1.01, it is also possible to kill Shub-Niggurath by shooting her, but you need to use rather a lot of cheat codes to do so (even with Quad Damage it'll take nearly 100 rockets).
Should you persevere in this task, one of two things will happen.
The interesting one is that you get to see an animation which assumes you used the "official" method of killing her.
The boring one is that the game might crash (I haven't seen this happen myself but other people have reported it).
To correct this bug, anyone with the QuakeC compiler could make the necessary 6-line modification to "oldone.qc" and recompile PROGS.DAT themselves (above the "self.th_die" line there should have been a "self.th_pain" line referencing a new routine which reset "self.health" to its initial value - in other words ordinary weapons should have no effect).
The bug was "officially" fixed in version 1.05 of Quake.