Base 5.  Another WAD file for DOOM II by Charles Gant.

So now your mission is changed a bit.  You are to secure a base that is expected to be invaded by those pesky demons from Hell!  The Base Personel has left you plenty of weapons and ammo, but... they also booby-traped the place!  You are to go there and secure the place for the impending invasion.  Just be sure you are heavily armed in case those demons arrive prematurely.  (Which we all know they will!)

Good luck!

This WAD file supports only 1 player, no deathmatch and all monsters show up in all skill levels.