Quake

 

More Passwords
By: Jesse Smith via The Unofficial "World of Nintendo!!"  and N64cc.com

Easy

?DRY OPFG P3BT VBKX     Realm of Black Magic
95RV TPFG QQBT JBJT     The ElderWorld
81RV 6PFG RGB5 5BJH     The NetherWorld
79RV 2PFG R7BS SBJF     Shub-Niggurath's Pit

Hard

2DR? OPFG Y3BP VBCX     Realm of Black Magic
1SR7 TPFG 2QBP JBBT     The ElderWorld
01R7 6PFG 0GBN 5BBH     The NetherWorld
Z9R7 2PFG 07BN SBBF     Shub-Niggurath's Pit

H40X ZVVB HLBD 74DJ     Level 2
H0P3 2XBN WQ2B NZVK     Level 3
CWHX CH3B GDB3 14JY     Level 4
PQW4 9QVD Y8VY X21M     Level 5
PL24 XBBT YJLQ 32?6     Level 6
6JR3 KDDV 3SLG 9RFT     Level 7
GWY6 7BBB 23BD L4HK     Level 8
B8YN BBBB ZBBB SXR4     Level 9
55R6 0XCJ 2LBR QVV1     Level 10
51RZ ?6xQ RGBR NNJH     Level 11
5XRV SMXP B7BR LP5H     Level 12
5SR9 TPFG VQBR JBCT     Level 13
5NRV JF6G CVBR GBFL     Level 14
5JR6 HDXM 2ZBR DPN5     Level 15
5DR0 HW4N PZ?S 5Y2W     Level 16
49R6 XBBJ 2GBQ 932T     Level 17
45RZ ZF32 LZBQ 773R     Level 18
41R0 6PFG WGBQ 5BCH     Level 19
4XRV QBFG B3BQ 3BD3     Level 20
4SR5 DBBN ZGBQ 1628     Level 21
4NRV JBBF BRY5 744W     Level 22
4JR5 1BBB 0QBQ X4HX     Level 23
39R9 2PFG W7BQ SBCF     Level 24
4DR1 4XDD RVBQ VM1B     Level 25

Normal

6DRW OPFG T3BR VBJX     Realm of Black Magic
5SR9 TPFG VQBR JBCT     The ElderWorld
41R9 6PFG WGBQ 5BCH     The NetherWorld
39R9 2PFG W7BQ SBFC     Shub-Niggurath's Pit

Nightmare

YDR8 OPFG 23BM V3BX     Realm of Black Magic
XSR TPFG 3QBM JBFT      The ElderWorld
W1R5 6PFG 4GBL 5BFH     The NetherWorld
VR95 2PFG 47BL SBBF     Shub-Niggurath's Pit

H40X ZVVB HLBD 74DJ     Level 2
H0P3 2XBN WQ2B NZVK     Level 3
CWHX CH3B GDB3 14JY     Level 4
PQW4 9QVD Y8VY X21M     Level 5
PL24 XBBT YJLQ 32?6     Level 6
6JR3 KDDV 3SLG 9RFT     Level 7
GWY6 7BBB 23BD L4HK     Level 8
B8YN BBBB ZBBB SXR4     Level 9
55R6 0XCJ 2LBR QVV1     Level 10
51RZ ?6xQ RGBR NNJH     Level 11
5XRV SMXP B7BR LP5H     Level 12
5SR9 TPFG VQBR JBCT     Level 13
5NRV JF6G CVBR GBFL     Level 14
5JR6 HDXM 2ZBR DPN5     Level 15
5DR0 HW4N PZ?S 5Y2W     Level 16
49R6 XBBJ 2GBQ 932T     Level 17
45RZ ZF32 LZBQ 773R     Level 18
41R0 6PFG WGBQ 5BCH     Level 19
4XRV QBFG B3BQ 3BD3     Level 20
4SR5 DBBN ZGBQ 1628     Level 21
4NRV JBBF BRY5 744W     Level 22
4JR5 1BBB 0QBQ X4HX     Level 23
39R9 2PFG W7BQ SBCF     Level 24
4DR1 4XDD RVBQ VM1B     Level 25
Full Arsenal Passwords 
By: Nick Leaf via IGN64.com
These codes will let you go to boards with a whole weapon arsenal.
Got to "Load Game" and press B to put in these Passwords: 
Board: Realm of Black Magic 
Easy: ?DRY OPFG P3BT VBKX 
Normal: 6DRW OPFG T3BR VBJX 
Hard: 2DR? OPFG Y3BP VBCX 
NightMare: YDR8 OPFG 23BM V3BX

Secret Level

Go to level 3, and near the end (before the elavator), there should be some platforms with two ogres on them above you. Kill them, and a cage behind you will open up, revealing armor. Wait, there's more than that. Shoot the wall behind the armor and there is a warp. Go into it, and you are warped onto the platforms. Go to the platform with some missles on it, face your right, and shoot the wall. This reveals a secret hallway with a warp in it. Don't go in it yet! It's a trap! The floor will open up, revealing lava. Sidestep to the right and run to the warp as fast as you can. You'll be taken to a secret level, Zigirat Viritgo. Only level four, and the game is playing with your mind! There is 0 gravity in this level and a tomb!

Enemies Kill Each Other

Turn on god mode, then turn off target mode. Hit a monster to make it chase after you. Run behind another monster. The monster you hit will damage the other monster and they will begin to fight until death. Grunts are the only monsters that will fight against themselves. If the monster you hit wins it will keep chasing after you until you kill it. If the other moster wins he'll stay in his orginal position until you hurt him.

Walk Through Walls

Enter NOCLIP at the password screen. This enables players to walk through walls.

Big Glitch

I think that Midway may have not known about the other exit in level 25. Why? Well turn on god mode and level skip and go to Shub's Pit grab the Rocket Launcher. If you have played the PC version you should know how to reach the other exit. If you don't know how I will try to descibe how to reach it. Get the Quad damage hidden in the room you get to by jumping off to the small ledge at the top of ramp. Teleport out to the Island and Quad Rocket Jump towards the wall over by the spot where you climb out if you happen to fall in the lava. The game will say completed and will start to say BUILDING as if there is another level. But nothing more happens the game is locked up. In the PC version this normaly takes you back to the start level. Did Midway miss this exit when porting over the game too bad they did not use this to hide an extra level.

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.