Marathon 2: Durandal was the first sequel in the Marathon series of science fiction first-person shooter computer games from Bungie Software. It was released on November 24, 1995. The game is mostly set on the fictional planet of Lh'owon, homeworld of the S'pht, and once again the player takes the role of a Security Officer from the Marathon.
Best video game of all time, IMHO. It's as perfect as electronic media can get.