Doom

Doom is a computer game created by id Software and published during 1993. The game is considered to be a cult classic among first person shooters. It was originally released as a free game, with only the first episode (Knee-Deep in the Dead) playable until players registered and purchased the rest of the game (episodes 2 and 3). A second version of the game, titled The Ultimate Doom, released the fourth and final episode (Thy Flesh Consumed).

Story
Doom's plot takes place on moons of Mars during testing of an experimental teleport which fails and creates a time-space warp into Hell, allowing demons to invade the surface of Mars.