One of the best suspense generating games ever.
First of all the music and sound effects are of a rare quality. They are a vital part of the game play because they constantly let you know when you're going to be in deep trouble and when you can relax. You could think that would give away the surprise of sneak attacks of the monsters luring in the dark. But it results in something different. Like in a good horror movie it creates the atmosphere, accompanies you and fires up the emotion the makers wanted to have you feel during the scenes. The music almost tells the story by itself sometimes. For instance when you play the alien hatchling an eerie, creepy theme is played, being exactly what you would feel if you realize that you have become a slimy snakelike monster.
The graphics are the best a directx 8.1 engine can give us. There is terrific light effects and the surroundings are diverse and believable. The overall story is somewhat cliché. But who needs a complicated story-line in a shooter anyways. The details are nevertheless worked out neatly. A general that has a grudge against the predator; a creepy scientist that is driven by nightmares about the Alien and turns out to make his own nightmare come true (hardly a spoiler) And the good old space marine on duty that has come to save the world from a disaster. And he tends to get emotional quickly when it comes to girls...
On top of that you play the alien, the predator and the marine during separate scenarios, and get engaged in three different ways into the plot of the story. This is as I mentioned a pretty unique feature in a game, especially when one of the characters is an out of the world creepy alien monster.
So why not a perfect score? That's just because it's a bit short and sci-fi shooters always have the trouble with believability. It misses the flirting with reality that half-life and return to castle wolfenstein have.
Anyways definitely worth playing.