My second level for Doom 2.There's technology,hell and cavern themes here.
Doom 64 MArine explains:
After killing more demons in the episode I call "The Outcast Levels",I thought that wouldn't have anymore open gates.I was wrong.But the biggest problem,the Motherdemon,is dead.Now I belive that the invasion will come to an end.Say it to your commander when he communicates with you. The commander says to you go to Drilla,an excavation site.Something is wrong in the lower part of the place.