According to the Union Aerospace Corporation’s (UAC) files, a space marine was sent to work for the company on Mars after he assaulted his superior who had ordered his team to shoot upon innocent people. His new job is to get bored to death whilst watching one of the company’s partners conduct inter-dimensional traveling experiments inside its radioactive waste facilities.
All of a sudden, there is a change of pace. The base on the moon of Phobos sends a distress signal, warning that something evil came out of their inter-dimensional gate, and the moon of Deimos just vanished. The space marines are called on Phobos to investigate. As the rest of the marines go inside the hangar, the one that had assaulted his superior stays outside to watch the base’s perimeter.
All the marine could hear is some screams and gunshots, then all falls quiet. Something must have happened to his comrades. With just his pistol, he steps inside to see what is holding them. His former friends have gone insane and are shooting at him. And he cannot believe that there are also demons inside a moon base throwing fireballs. A job is a job however, and the marine proceeds forward through the moon’s facilities in order to find the root of the problem.
Quite a number of areas on the moon’s facilities are inaccessible, and brute force does not work. So the marine ends up looking for all sort of key cards in order to go on, not to mention rationing the ammunition and medi-packs that he can find. Stepping from the computer station into the next area, things seem immediately out of place. It is an anomaly, and evil is creeping out of it. Two Barons of Hell step out of it, and only some good old rocket fuelled shells from mother Earth can dispose of them.
On the other side of the portal, the space marine finds himself on Deimos. The different surroundings are instantly apparent. The demonic imagery for one, and the cacodemons spitting their putrid bile on sight. And this is only the containment area. Who knows what lies beyond the moon’s central complex? But hey, our hero manages to find a plasma rifle, and prepares to fry some hellspawn.
As the neat lab walls make way to rotten walls and decayed bodies, the foreboding feeling of a huge demonic presence is in the air. It all leads to the tower of Babel, where a cyberdemon, a huge ugly monster with a rocket launcher instead of his left arm, awaits to start his feast. The space marine has other plans though, and manages to slay the beast. However, his hopes are trounced soon after, when he finds out that the moon he is on is floating above hell itself.
The space marine steps down on the surface of hell. The walls are alive, but at least it’s not too hot in there. The hell keep is one hair-raising place, but that is not going to stop the gun-toting earthling especially after he gets his hands on the BFG-9000. His death-dealing run ends with a final confrontation with the spiderdemon, essentially a huge brain with mechanical arachnid legs and a rapid fire chaingun. As the wailing beast explodes, it is time for humanity’s saviour to return back home.
After the mastermind dies, hell itself falls quiet. A doorway opens in front of the space marine and takes him back to the earth. He is home at last. It’s time to see what has changed during all those years whilst he was exiled on the red planet. Ugh, but something seems awfully wrong. Is this all true?