With the traditional summer gaming drought behind us, Bioshock is the first proper, promising-looking title of the pre-Christmas flood, and it’s unique in many ways.

For starters, it isn’t a sequel or a cheap movie cash-in. It also defies classification, blending aspects of first-person shooting games with elements of role-playing and survival horror. But the thing that really sets Bioshock apart from the current crowd is that it features something not often found in video games: a decent story.

Things start with a bang when a plane crash leaves you stranded in the middle of the ocean. One accidental bathysphere journey later and you’ll stumble across a bizarre underwater Art Deco metropolis.

An old public information film explains that the city of Rapture was created in 1946 by an idealistic fellow named Andrew Ryan, as a kind of experimental utopian society, free from government and religion. But as soon as you start exploring, it becomes clear that something went very wrong indeed.

It’s an intriguing setup, and one that encourages you to carry on playing, if only to get some answers. And the plot thickens further when you discover that Rapture’s bio-engineers have been messing about with something called plasmids: bodily enhancements that invest the user with special powers, such as the ability to zap people with a blast of electricity.

The ruined city’s demented denizens aren’t exactly welcoming and you’re soon using plasmids yourself in an effort to stay alive. Conventional weapons are also available, but you’ll often find your new powers are more effective than a pistol or shotgun – especially once you have started to upgrade them.

The trouble is that in order to feed and build up your powers, you’ll need to keep your eyes out for a substance known as Adam, which turns out to be a relatively scarce commodity. To make matters worse, you’ll need to contend with the disturbing double-act of the Little Sisters and Big Daddies.

We don’t want to spoil the plot for you, so let’s just say that these unusual adversaries will eventually force you to make an uncomfortable decision that will have a knock-on effect throughout the game.

On the technical side, visuals and sound are a genuinely excellent, though a certain amount of processing oomph will be required on the part of your computer, to enjoy all the game’s graphical flourishes.

Hints of George Orwell and moral debate are blended with high levels of action, adventure, blood, guts and gore. Bioshock is definitely a grown up’s game – something that’s reinforced by its corresponding 18 certificate. As such it won’t appeal to everyone, but it’s definitely one of the more thoughtful shoot-'em-ups you’ll find on the shelves, while its watertight presentation and sparkling originality provide a distinct breath of fresh air.

Vista compatibility: Yes