As far as opening sequences go, Prey pretty much nails it. I won't spoil it, but the gist is that Tommy (a Cherokee man), his girlfriend Jen, and his grandfather, are taken to an alien colony. In typical sci-fi story fashion, these aliens harvest humans for food, so when grandfather bites the dust (not as big a spoiler as you might think) and you're separated from Jen, you're in somewhat of hurry to rescue her before the inevitable pulverising.

What plays out would be a pretty simple ‘good guy versus aliens' shooter, but things are shaken up by the ‘clever' use of gravity, portals, and the ability to ‘Spirit Walk'.

This means that you can float, scale walls and basically throw all sense of reality out the window. Prey really does mess with your head - throwing up some insane level designs and a few tricky puzzles.

Much has been made of the ‘Portal' technology seen in Prey, and to be fair it's pretty damn cool - at least for the first few hours. They're basically one-sided doors suspended in air that take you to another part of the level.

This is actually much cooler than it sounds, as you can peer into these portals, seeing the area you'll be teleported to, and even see enemies launch an attack through the portal door. From an early stage in the game Tommy is given the ability to Spirit Walk.

You can take control of his spirit (while his body hangs motionless in the air) and in this alternate world you can see and use things that aren't in the mortal world. Armed with a bow and arrow, you also have the potential to cause a lot of damage, but you'll need to return to Tommy's body in order to make your way through the majority of the levels.

There are a few clever puzzles here and there, but at times you'll wonder why it's necessary to continually repeat the same set of actions While the pros and cons of the portals, changing gravity and spirit walking can be argued, the weapon selection is top drawer and nicely varied. The current trend to limit weapons you can carry is gladly nowhere to be seen, so after a while you'll be carrying a sack load of guns, all deserving their place in your arsenal.

Each weapon also includes a secondary mode, with everything from a grenade launcher for your machine gun-like weapon, to a recharge tool for the rather excellent Leech gun, capable of using numerous energy types as ammo. At times you will be faced with so many enemies that your more powerful weapons run dry, so you'll be forced to fall back on your standard Hunter Rifle. Thankfully this never runs out of ammo and can double as a very handy sniper rifle.

At various points you'll hop into a small spaceship, equipped with a tractor beam and a gun. Because you can move around in all directions within the 3D space the controls become awkward at times, but on the whole the vehicle sections break up the gameplay quite nicely and the powerful weapon lets you dispose of enemies without much trouble. Being swamped by enemies isn't a prevalent problem, but as the action heats up towards the tail end of the game, it does occasionally verge on overkill.

Thankfully you can't actually die, not in the traditional ‘game over' sense anyway. When you ‘die' Tommy is taken to the Death World. Here you'll be in spirit form and must take down as many wraiths as possible, replenishing your health and spirit gauges as much as possible before being returned to the real world. This could very easily be seen as a cop-out by Human Head, implemented in order to side-step choke points within the game, but it works.

The soundtrack is the star of the show, with some brilliant tunes and a collection of great licensed tracks that crop up from time to time, although perhaps not often enough. Weapon effects are solid, and while the aliens don't really say much, they sound great and never irritate due to overuse of certain sayings. Tommy can often be heard shouting amusing swear-filled sentences as things happen in the game, and the voice acting across the board has been handled well. Full online Deathmatch and Team Deathmatch play is included, and it has a rather unique Prey twist.

Game modes are pretty standard, but it's the way the maps are designed that makes online Prey a completely different experience to what you'll be accustomed to. Walls can be walked on, players are running around all over the place, above, below and beside you, and it's utter chaos.

Spirit walking is also available, but your spirit gauge will gradually run out over time, meaning you'll have limited time to make a kill. It might be a little too insane for players that prefer traditional Quake and Unreal Tournament gameplay, but it's great to play something that's not a carbon copy of every other online game on the market.