Doom Secret Options:

Commandline Parameter: - debugfile (opens a debugfile)
                       - devparm (press F1 to make a screenshot)

Commands in the Game: 
 ID DQD      -God Mode
 ID KFA      -Full Ammo
 ID DT       -Full Map and Locations of Enemys (2x)
 ID BEHOLD I -Parly Invisible
 ID BEHOLD R -Toxic Resistent
 ID BEHOLD V -Invert View
 ID BEHOLD S -Red Touch (?)
 ID BEHOLD L -Light
 
Example: To enable God Mode Press "IDDQD"
         To enable Light Press "IDBEHOLDL"
         
Unknown Commands: 
 ID CHOPPERS - ?
 ID SPIS     - ?
 ID POPD     - ?
 ID CLEV     -Maybe Jump to Level ?
 ID MYPOS    -Somekind of Position marker ?