Abbreviation for First Person Shooter", a video game in which the player sees from the perpective of the main game character, or in the "first person". These games usually involve some type of weapon, usually a
gun, of which the end of the barrel can usually be seen at the
bottom of the screen, as if the player is looking down the
gun.
Some examples of F.P.S.'s include Battlefield 1942, Half-Life,
Doom (perhaps being the most famous, and arguably the first
real F.P.S), Red Faction, and the Medal of
Honor series.