BioShock 2

Andrew Ryan, the Citizen Kane of the seabed, forever railing against conformity, against predictability, against the things that hold men back from greatness: what would he think about sequels?

Actually, who cares? For the moment, it's just good to be home again. It's good to hear the echo and churn of Rapture's creaking rafters one more, and it's a thrill to have discovered a bit more of Ryan's glitzy, waterlogged underworld to mess about in. A chance to play through the first few hours of 2K Marin's BioShock follow-up reveals the city's new custodians are pretty pleased with things, too. They certainly waste little time in thrusting you back into that rumbling, corroded temple of the depraved and pitting its fallen population against you.

It's almost impossible to mention BioShock without turning your mind back to the original game's opening moments, remembering how jarring and how terrifying it was to be dumped into all that black water, surrounded by jagged walls of flame, while the tail of a passenger plane sank below the waves behind you.

The opening to the sequel is equally memorable, although previews (like this one - sorry) will have inevitably lessened the impact somewhat. Once again, water ripples and light flickers. Slowly, an image stabilises, and it's you - the hero? - peering into a murky puddle as your own reflection stares right back, all hulking shoulders and shiny brass face-plate with its thick, foggy glass.

Details are king in Rapture: the Incinerate Plasmid comes with the reminder that it's for ages 12 and up only.

You're a Big Daddy (the first one ever, brought back to Rapture for reasons as yet rather mysterious) and as you start to move, you feel the plodding heft of a Big Daddy in every step. Look around and you're likely to see the rim of your headgear obscuring the outer edges of your vision. Stand and your drill arm snaps into view at the bottom right of the screen. Take a few steps, and listen: You're back in Rapture in its groaning, dripping, flickering glory. Much has changed, and so, most importantly, have you.

Time has passed, and Ryan's paradise has spiralled even further into chaos. Any surviving Splicers are now grotesque mottled freaks, all split lips and blistered skin. Elsewhere, the city's constant architectural grumbling seems a little more insistent, and dereliction has dappled the walls of its palaces, theme parks, and railway stations with sea urchins and glowing coral, while aging speakers spurt wobbling chunks of old dance-hall music at you. You're never far from something that's sputtering, sparking or unevenly chugging down here, and figures hide in every shadow, ready to finish you off with spanner or tommy gun.

At least that last bit should be familiar. For the first few hours of the game, the biggest change, other than the general deterioration of the environment, is the drill where your right hand should be. Good. Combat was arguably the aspect of the original BioShock most in need of tweaking.

The blend of plasmids and firearms proved endlessly fascinating for those willing to really put in the effort, but for lazybones like me, it was too easy to ignore the game's regular promptings to sound out the environment for devious bottlenecks built for ambushes, and settle instead for a repetitive slog through lumbering enemies, sluggish weapons, and endless sentry turrets. If you weren't careful, combat could eventually become nothing more than the busywork price you paid to unlock the next bit of story, or the latest stylish chunk of art design.

The drill changes a lot of that, providing every kind of player, regardless of their approach to combat, with something devastatingly satisfying to focus on from the off. The torrents of claret that ensue every time you chew into an enemy might be there to disguise the fact that the animation itself doesn't have the greatest sense of connection, but the feel of the weapon, and the ease with which you can chug through Splicers with it, gives BioShock's often rather cerebral approach to death-dealing a much-missed visceral kick.

Nothing in Rapture ever comes for free, mind, and the drill has a cruel hunger for fuel to keep it spinning. That gives you one more dial to keep an eye on, and one more reason to loot the bodies of your enemies. Even when it's out of juice, however, you can still swing the thing in a brutal melee move that is, weirdly enough, a lot more visually satisfying than the stronger attack.

Aside from the drill, there are other new weapons to try out, like the rivet gun. It looks like something Heinz Wolf's steampunk granddad might have constructed to kill wasps, and it fires weighty slugs that punch into your enemies but leave an agonising pause between rounds. It takes various types of ammo, too, such as trap rivets, which give you even more options to get the drop on your foes when you're running low on Eve.

The best new gadget revealed in BioShock 2's opening hours isn't a gun, however: it's a research camera. Liberated fairly early on in proceedings, it allows you to sound out Rapture's baddies for weaknesses, gaining permanent perks and damage boosts in the process. The rub is that unlike the original game's camera, you can only capture the info you need by recording enemies while you're attacking them - a move which creates a pleasantly terrifying scramble as you switch the camera on and then start dealing out damage before someone puts an open-ended adjustable wrench through your islets of langerhans. (Google it. Actually, don't.)

Hacking has taken a turn away from puzzling and towards twitchier skills, but it's no less satisfying.

The camera adds a pleasant twinge of extra challenge to the average Splicer, but it's truly unnerving when you fumble to use it against some of the more dangerous foes like Big Daddies - particularly since you need to mix up melee, ballistic, and plasmid attacks in order to get the data you need. At the very least, it's an excellent means of forcing less imaginative players like me into embracing the levels of complexity that truly bring the series' combat to life. I tried new things out because I had to - and then I started to wonder about what other things I could try.

New weapons call for new enemies, and that means hulking nasties like the Brute Splicer, a huge damage tank who lobs pieces of scenery at you, and sits somewhere in between common grunts and Big Daddies in Rapture's ecology. He may have wandered in straight from Left 4 Dead, but we're happy to have him, and at least he put a shirt on.

Then there's the Big Sister, decked out in braces and leg supports and stomping into combat like the world's narkiest polio sufferer. Her semi-regular appearances are accompanied by an unpleasant screeching as she bounds acrobatically around the scenery. A match for you in both brawn and brain, Big Sister Moments tend to end explosively, indicating 2K Marin has inherited Irrational Games' (yay!) fearsome stage-management skills.

Even when you're pitted against the regular foot soldiers of Rapture, BioShock 2 ups the ante. As a Big Daddy, you're often required to protect a Little Sister as she harvests Adam, an activity which also happens to throw the local crazies into a frothing frenzy. For a few magical minutes whenever harvesting occurs, 2K's classy dissection of 20th century philosophy becomes a very pretty take on Smash TV; such impromptu arena moments are the final proof that 2K Marin's made the combat a lot more immediate and enjoyable.

The studio's gift for disquieting juxtaposition helps, too: any game that shoves you into a blood-soaked street fight against waves of women in pearls and sensible calf-length skirts while "How Much is that Doggy in the Window?" plays in the background must be doing something right.

New areas are as promising as the new tools you'll get as you explore them. I'll be brief here as, more than with almost any other game, environment and narrative dovetail so closely in BioShock that revealing too much of the former is almost certainly spoiling the latter. Suffice to say that, fairly early on in the game, you'll spend a charming half hour or so hunting through Pauper's Drop, the world's most unpleasant hotel - and I'm taking into account the Travel Lodge near Stansted airport when I say that.

It's a rough sprawl of crumbling hallways and miserable bedrooms with sharks flitting by outside and reminds you, in case you were in any danger of forgetting, how much can be gained by a skilful blending of the domestic and the other-worldly. You'll be exploring the hotel with an angry voice in your ear, too: the voice of an elderly woman hell-bent on telling everyone what an awful person you are. Before you leave, you'll have the chance to prove her right, should you wish to do so.

BioShock 2's not short on angry, even evangelical, voices, actually, the warring radio messages of Atlas and Ryan replaced, at least in the opening hours, with those of the first game's Dr. Tenenbaum and new antagonist Sophia Lamb. Tenenbaum's presence is unexplained as yet, but Lamb's far more openly complex - a messianic mother figure with a serious following. Graffiti left by her acolytes tends to have a distinctly spiritual bent, and Pauper's Drop kicks off with you stumbling into what looks quite like some manner of grim religious ceremony. If the first BioShock concerned itself with the dangers of the self, the sequel may well be turning its attention to the prickly allure of other realms entirely.

The architecture of Rapture, with its distant towers disappearing into the murk, is as wonderful as ever, carrying with it a distinct hint of the work of Hugh Ferriss.

Whatever dark treats Lamb and Tenenbaum ultimately have in store, BioShock 2's narrative quickly becomes a compulsive delight. As with the first game, however, the minute-to-minute agenda is slightly less engaging. Life in Rapture, even for a Big Daddy, is still often a case of "go there, find that, and bring it back", with the game's opening hours hinging on your gradual journey across the city by means of a train, with regular stops at various stations along the way as you clear track blockages via the medium of controlled exploration and fetch-quest.

That's more than enough to keep you playing, of course - and it's hardly that different from most other games' agendas - but because BioShock tends to bring such weighty thematic ambitions with it, you can't help but hope for game mechanics and structures that equal them. You're the first Big Daddy, the man who defines this world and - some would say - kicked off its slow corrosion. It's a little bit odd that, for the opening sequences at least, you're mostly dealing with the wrong kind of snow.

That said, there aren't many developers who would risk such enormous budgets and employ such obvious expertise on a fairly downbeat tale in which ritualistic child abuse plays such a central role, so it's hard to begrudge the designers a less than entirely inspired first act. Train tracks aside, BioShock 2 is looking thoughtful, moody, elegant and smart. The first few hours almost certainly have what it takes to meet your expectations; only the rest of game can tell whether 2K Marin will be able to subvert them, too.