A first-person shooter. With aliens. On a spaceship. Prey's basic premise isn't the most original game idea ever. Perhaps developer Human Head's next game will be an RPG which involves a small amphibian, who is faced with a momentous task; to cross the motorway of Thran'gal and then hop over the tumultuous rushing river of Nix'thran on logs, before reaching the lily pads of...

So we're being a bit silly. In all fairness Prey was conceived a long time ago, when level designers wielded wooden clubs rather than mice and, in fact, wore loincloths and smashed small beasts over the head rather than designed levels. Yes, way back in 1996, when the game was undoubtedly a more innovative idea. The question is, has the decade of on-and-off development been worthwhile? And the simple answer is yes.

Okay, the premise isn't original. Neither does Prey try anything fancy, as it's a thoroughly linear shooter. It does, however, take some fresh ideas and execute them with a definite shine. The cornerstone of the design is that being on board a spaceship should have physical consequences. In one word - gravity - which isn't as much of a downer as Newton would have you believe.

In fact, the gravity on board Prey's alien vessel can have you all over the place. It's slightly freaky when you first walk down a corridor and glance through a window to see alien warriors pelting across the ceiling of the room next door. Although it's even more disconcerting when you step onto your first gravity field walkway and start running up a wall yourself.

We can't stress enough how disorientating this is; having a firefight against three aliens and trying to duck into cover is made that bit harder when you're unsure exactly where the ceiling's gone and which way is what. The net effect is an actual sense that you really are on board an interplanetary cruiser.

Prey throws plenty of simple puzzles at the player, of which many are based on switches that change the gravity field in the room, so the left wall can become the floor, allowing you to walk to a previously inaccessible place. Combine this with portals - rips in space which teleport you to other locations - and you've got quite a concoction of futuristic travel modes.

Juxtaposed against this is the game's other novel element, which is mythical in nature. The protagonist is an American Indian who can leave his body in a trance and spirit walk. This can be used to scout ahead, as you're largely invulnerable, and some puzzles require spirit form in order to solve, which adds variation in that department.

Where Prey falls down a little is in the design of the puzzle elements, which can at times tend towards the repetitive and simplistic. However, the game's sensible enough to keep moving along at a swift pace so you don't get too hung up on these issues.

The levels are reasonably compact and you never go for long before you're encountering something different, whether it's a new gun, a weird space vehicle or a slobbering alien boss monster with six rows of teeth and a distinct halitosis problem. Sometimes it's simply a breathtaking view of the Earth below - did we mention that the graphics are stunning?

The ship looks fantastic, mixing acres of metal with disgustingly slimy organic tubes, and bits of scenery which have been sucked up from our ravaged home planet. Attention to detail is rife, right from the very first scene when you're in a bar, pre-abduction, and you can play the video poker machines, change the tune on the jukebox, even use the taps and hand dryer in the bathroom.

Driving all this is the engine of the storyline, which is never intrusive (there are no cut-scenes) and always compelling, even if it does include typically unoriginal "must save the girlfriend" elements. To go into specifics here would be to spoil it, but suffice to say there's enough mystery, with ghosts in the machine and an enigmatic computer, to keep you playing in the name of finding out exactly what the Hell's going on.

On the multiplayer front, Prey only offers plain old vanilla deathmatch, which is perhaps a touch disappointing. On the plus side, though, elements like switching the gravity in the midst of combat make online play far more interesting and tactical than your average Quake-style blaster.

Prey is not only a visual feast, it also boasts some fresh ideas and a compelling storyline which runs along at pace. True, it's very linear and occasionally flirts with the repetitive, but that's no reason to avoid strapping on your gravity boots and taking a trip into space.