According to scattered reports from fans and press releases, the makers of Aliens vs. Predator couldn’t implement a save-game feature because the enemies for each species are randomly placed for each game. Each saved-game file would be prohibitively large.

I’m not so sure that makes up for the utter despair brought on by fighting through, say, a horde of aliens, patting oneself on the back and immediately being killed, only to face having to replay the entire level. Besides, the game itself is under 300 megs, which these days is less than usual.

That is this game’s most glaring weakness, and indeed one of its only flaws.

At the outset, the player can choose to be an alien (here called xenomorphs), Predator (the intergalactic hunter from the movie series of the same name) or a hapless Colonial Marine caught between the two. Each race has a minimal backstory that really should have been fleshed out because, well, each is so interesting.

That story features a clip of movie goodness, and then it’s straight into the fray. Well, okay, the first level serves very much as an introduction to each race’s various pros and cons. Yet even on the easiest setting, players should expect to die. A lot. And that means starting over a lot.

Yes, it does get easier, and the player should even soon be in a rhythm that makes surviving "episodes" more frequent. Then it’s almost possible to enjoy what a truly remarkable world Rebellion and Fox have built.

The graphics here are by far the best I’ve seen in a first-person shooter. Better yet, they’re pure "Alien," with rainy landscapes and claustrophobic biomechanical tunnels and dark tunnels lit only by flashing emergency lights. Many areas are, in fact, pitch black, though each race has different visual modes for navigating this nightmare world.

You will jump, no matter how hardened you think you might be. Enemy AI is extremely well done; don’t think you’re safe with your back against a wall as either the marine or Predator, because those durn aliens have a bad habit of traveling through vents and ducts and even metal walls.

The world is fairly interactive. Objects can be destroyed; weapons scar the surroundings. Even better, these graphics don’t seem to be a huge drain even on moderate systems. Control is smooth, although the strafe buttons are oddly placed. That may mean falling from cliffs accidentally, but only until the player gets used to the controls (or changes them).

Let’s meet our heroes, shall we? The Colonial Marine is a private who somehow oversleeps and is left behind by the rest of his squad. Luckily, they can access the base’s comm facilities, and so direct the player from afar.

The alien is a recent hatchling part of a hive living in an ancient temple. Those poor humans have uncovered the temple, and now it’s time to chow down.

The Predator just wants a fight, and this looks to be the battle of the century. Strangely, there are allusions to the Marines fighting and killing another Predator; why are there two? Here’s where the backstory would be useful.

Each race has five episodes; each of those takes place in a different location with several tasks to accomplish. Better yet, finish the episodes in the right combination of difficulty levels and the player can access hidden "bonus" episodes.

Fans of either movie or FPS games in general would do well to pick this up. In fact, those veteran gamers who scoff at save-game features constantly must add this to their collections. Casual players might want to hold off; the lack of save ability really does make this game extremely tough.