Type in the following codes while playing the game.
iddqd - Permanant Invunerablilty (Type again to undo) Can be used to boost your health to 100 if you don't want to have all weapons
idfa - All weapons and ammo
idkfa - All weapons, ammo and keys
idclip - Allows you to walk through walls and enemies, but you can't pick anything up in this mode. Type in the code again to undo cheat
idclev~ - Level skip. Replace ~ with a number to skip to that level
idmus~ - Music change. Replace ~ with a number to change the music to the music for that level number
idbehold~ - Gives you a power-up for. Replace ~ with the following to get the power-up:
I=Invincibility Power-up, R=Radiation Suit, S=Beserk Pack, L=Light Amplication visor, A=Auto Map
idmypos - Gives you location on the map, and co-oridinates as well (I think)
idchoppers - Gives you a chainsaw and a mildly humerous message at the top of your screen
If you play the challenge made by the final boss backwards, you will hear him say "To win the game you must kill me, John Romero".
Type t in the map to enter talk mode. Hold [Alt] and type iddt several times. This will reveal the entire map. Repeat the code to reveal all items. Repeating the code again will return the map to normal.
spawn to a prison with zombies in every cell bloody of course. with blood on the wall and stuff. unlock the cells if u want. all guns. lights go on and off and any more scary things u can think of once you go to the end of the hallway a scary face pops up on the screen and screems.
Hold [Alt] and type iddtiddtiddtiddt in map mode.
Start the game with the doom2 -turbo 250 command line to have your player in turbo for the entire game.
At the final level, type idclip to enable the "Walk through walls" code. Go through the wall with the demon head on it. You will see that the final boss is the head of John Romero, the co-creator of the Doom series.
Go to level 30, Icon Of Sin. Collect all the items, then enable the iddqd code. Go through the warp, then enable the idclip code. Go backwards until you get to the skull switch. Blast the demon that appears with two rockets to kill it. Activate the switch. Go on the rising platform using the idclip code. Do not walk through the wall of the demon. Blast the demon's forehead (the part that makes skull boxes). This will hit the head on a stick inside. You should be able to hear a roar. The rocket box on top of the platform can be collected an unlimited number of times, unless you collected the box beforehand.
If you run up against a wall at a 45-degree angle, you will move at a very fast speed! This is great for speedruns.
Type idclev32 or idclev31 during game play to restart in a totally new level. When you complete one of those levels you will always start on the level suburbs and continue your Doom 2 game.