The year is 2145 and humans have managed to travel to Mars. The Union Areospace Corperation have constructed a facility on Mars to research ways to abolish the earth energy crisis. Their form of energy? Energy extracted from Hell.

Of course, extracting energy from hell is a bad idea, but they didnt see that. They spent long years, researching the different demons and architecture of Hell. They even managed to capture the Baalger Demon at a cost of a life. They even created their own demons by using hell energy known as The Lazurus Wave.

The demons rank from the lowly Lost Souls to the Baalger Demon (which they added cybernetic enhancements to it creating the Cyberdemon) but they are all scared of one thing, the thing that defeated the representation of all evil, the Icon of sin, the thing that is driven by pure rage. The one thing that SATAN himself fears and hides in the shadows...THE MOTHERF***ING DOOOOM SLAYER.

The UAC went on an expedition to Hell, led by the facility's leader Dr Samuel Hayden, who recently was transfered to a robotic body. There they discovered many secrets and artifacts, one of which was a coffin which contained...The Doom Slayer. The demons protecting it had ferocity previously unobserved.

Then one day, the leader of the Lazrus Wave Project Department, Olivia Pierce, opened a Hell portal to Mars. The demons invaded and overran the facility in a few moments of time. However, something terrible happened to the demons, the Pandora's box was opened. The demons had awakend light that shines upon us all.

The Doom Slayer.

The demons were DOOMED.