Doom

Normal cheat:

During play, type the codes with the keyboard.
You don't need to hit [Enter] after the code.
After entering, a message should be displayed at the top of the screen telling which cheat mode was activated.

iddqd Degreelessness mode (God mode)
idkfa Very Happy Ammo (full ammo, 200% armor, all weapons)
idspispopd No clipping (you can walk through walls)
idbehold Displays menu (followed by S, V, I, R, A, or L)
idclev Warp (add episode and level number)
idmypos Displays your coordinates in hex
idchoppers Gives you the chain saw
iddt Toggles Automap between normal, full, and full with objects
(enter when looking at the Automap)

Junkies cheat:

Iif you are really addicted and haven't got enough with the previous cheat, here are more goodies.

You get :

- A demo-movie showing how to get to a secret hidden level
- Instructions on how to use the infamous command-line parameters and how to build your own Doom-virtual-reality-setup !

It is a all in the included file. (Information from Cheat Machine)