May i be the Captain Obvious, but this one is FULL soundtracks collection for early 'DooM' games. Including PC originals, Add-On-s, rewarded (and/or official) WAD-s, PSOne ports (incl.Final Doom), and many extras.
Well, if you are really a 'DooM' fan...
P.S. Can't find tracks from "DooG Slayer" (fanmade game with Inugami Korone).