So, anyway, DOOM wasn't the very first first-person shooter, but many believe it was the game that defined the genre. It added so many new things that would help shape the history of FPS's. Hell, if it weren't for DOOM, you wouldn't have any of your fancy Halo or whatever FPS's you play.
THE STORY: Our hero is a marine on Earth, sent to Mars for attacking your commander for order to fire upon civilians. There are 3 facilities located on and around Mars. One, of course, on Mars, one on Mars' moon, Phobos, and one on the other moon, Deimos. All these facilities are led by the Union Aerospace Corporation, which does research "for the better of man". What the public doesn't know is that the UAC has been experimenting with "alien" teleporters which were found on the moons of Mars. While experimenting, many people have been actually "lost" in the teleporters and never returned. One day, something unknown came through the teleporters. "Aliens" started pouring out of the gates and taking over each facility. A distress call came in and our hero ia off to Phobos where the call came from. He must hold his position while, his company enters the Phobos base. Things didn't look too good as he hears screaming, firing, and some unknown noises from the radio. After a few hours, there was silence. He is the only one left, and the only way off Phobos is through the base.