You need Plutonia IWAD for this. Plot: Urania - a planet that suddenly appeared in the solar system. Many years ago there lived advanced civilizations, and now it is teeming with monsters. You were sent to Urania as part of the international battalion, in order to eliminate the cause of the monsters spawning from portals which terrorize the population and prevent us us excavate on the nearby planets. But now your comrades are killed and you are left alone face to face with an army of monsters on an alien planet.
ID Software for Doom. Nick Baker for textures. Blue Shadow for switches.