You are a marine who has crashed landed on a planet along with several other marines. It does have ok graphics, even though they are mostly yellows, browns, and oranges.
Replay value is somewhat lacking.
The only reason I would recommend this game is if you have every game under the sun but this one. Go out and buy Deus Ex so you can get your moneys worth out of a game. Another classic from id software again. Quake 2 has a nice SinglePlayer mode, that actually even features quite some replayability and then of course has a BIG multiplayer aspect. Capture the Flag in Quake 2 is still the best implementation of this mod to date.