Here is a list of every cheat code for Doom II

Just type these in anytime while you are not in map mode.  You don't have to press enter after the end of them.

• IDDQD = God mode.
• IDKFA = All ammo, weapons, and keys.
• IDFA = All ammo and weapons, no keys.
• IDDT = Shows all of the map, type in again to show everythings location on map, type in again to shut off.  In Deathmatch or Nightmere hold down the ALT key and type in this code 4 times then release ALT key to make work.  NOTE: You must be in map mode for this one to work.
• IDBEHOLD = Powerup Menu, type the first letter of what you want from the menu to get it.
• IDCLIP = No clipping (walk through anything).
• IDCHOPPERS = Gives you the chain saw.
• IDCLEV = Warp (followed by 2-digit map number).
• IDMUS = Change music to certain maps music (followed by 2-digit map number).
• IDMYPOS = Displays your bearing and coordinates in hex.

Try going to ID Software's web site for patches and updates on Doom II.