Left 4 Dead 2

Valve dragged us into its gaming dungeon on the hottest day of the year to see an equally sizzling new build of Left 4 Dead 2, running on banks of PCs and 360s, revealing the second half of the Parish campaign unveiled - and previewed by Oli - during E3. No frills, no grandiloquent pronouncements, just a quick hello from Valve's affable marketing boss Doug Lombardi, and then an opportunity for us to get stuck into the sequel to last year's sensational co-op shooter.

The two previously unseen stages on offer couldn't be more different in terms of pacing, approach and strategy, and point towards the increased variety and scale Valve is aiming for in the follow-up. If you've been following the flow of information since E3, you'll know the headline additions, but to recap: a new cast of characters and storyline; a new location (from the plantations of Georgia to the swamps of Mississippi); melee weapons (including a frying pan!); new boss zombies; the Wandering Witch; an AI director overhaul; 'gauntlet' moments; and more features still to be announced.

But the core experience of group survival in the face of overwhelming odds of course remains. And despite the checklist of new features, Left 4 Dead 2 looks and feels very much like its predecessor at first. Which doesn't fit any definition of "a bad thing" I've ever come across, although opinions differ in certain quarters.

New guys Nick and Rochelle take to the New Orleans streets.

The first new stage is a tense, nerve-wracking run through a battered New Orleans suburb in daylight. Survival under the sun is another signal addition to the sequel, adding visual variety. And if you're thinking that might strip away the tension, fear not.

The environment is a tightly structured, claustrophobic rabbit warren of rooms across multiple storeys and multiple blocks. The constant, creeping fear that a zombie could emerge from around a corner, through a window, up a stairwell, from any direction, is shattering. And this is skilfully managed by the AI director which, for the most part, drip, drip, drip-feeds danger on the squad, while all four players wince in expectation of the inevitable flood.

Zombies are spied lurking alone through windows, or shambling along in small groups, but rogues are liable to storm in at any moment. Nothing, however, punctures the tension quite like stepping into a room as a boomer wretches a Jackson Pollock all over your face and, while stumbling in a vomitous blur, gun flailing wildly, a hunter savagely pins you to the floorboards. It's classic Left 4 Dead, and the fractured layout of the town here makes it all the more critical to adhere to the game's caution to stick together unless you want to go home in bin bags.

The axe lets you slice off individual limbs. Amazing how he keeps that suit clean.

The horde moments come in the broader open spaces between buildings. In one section the onrush is triggered by starting a discarded carnival float. And the myriad tiers, balconies, roofs, nooks and crannies are quite the playground for a wily AI director, with plenty of scope for strategic variety.

New weapons make an appearance. Oli mentioned incendiary upgrades in his E3 preview. Here, it's deliciously satisfying to pop a round through a window frame from the street, and watch the room - and zombie - go up in flames.

Melee weapons are also in evidence. We're still frustratingly denied the most promising of all - the chainsaw - but the frying pan is an hilarious addition, while the axe, as well as making a fabulous noise as it tears through flesh, lets you hack off individual limbs with a careful aim. There's clearly much amusement to be had from hacking off a zombie's arms while it continues to lunge for you; or neatly de-legging one that's towering above you on the bonnet of a car.

Project lead Chet Faliszek tells me the axe can be used to one-hit kill a Witch, if you can successfully sneak up behind her. And it's likely there'll be a dedicated Achievement for that. "If you did that with a frying pan, you're going to have a bad experience," he adds, grinning.

Towards the end of the stage, we're heading down a street, with three-to-four storey blocks on either side. Suddenly, zombies are streaming from top-floor windows in a torrent, before flowing towards us like a slavering tsunami. A great moment.

Reaching the final safehouse proves relatively straightforward in the end. And utterly useless preparation for what comes next. The finale of The Parish is the first example we've seen of 'gauntlet' gameplay, new to the sequel. Starting at one end of a bridge, your party has to make it to the other end, where - a radio message informs you - a rescue helicopter is waiting. There's no holing up and surviving until help arrives. Your mission is literally, and in the best Arnie voice I can muster: "Get to the chopper!"

What plays out is an astonishingly relentless trek down the bridge, clambering over upturned cars and crashed trucks, while crashing waves of zombies burst towards you in a seething, ceaseless flow. There is no respite. There is nowhere to hide. There is only forwards. And if you die, you die. It's up to the remaining party members to push on regardless.

The pile-up of broken motors littering the roadway means that, while the zombies are all coming at you from a narrow, defined space up ahead, their sheer volume means you're under constant threat from those splitting off from the pack to scurry up and down the bridge structure to flank you or box you in from the rear. The closest things to a corner to cower in are open truck containers, which is where to find ammo pickups and the like. But there's very little point in hiding away here other than seizing an opportunity to heal yourself.

Not everyone was pleased with the addition of daylight missions.

One moment sticks in the mind that sums up the frenzy. My character and another had fallen off edges (there are also great holes ripped through the roadway at various points), and were clinging on for dear life, waiting to be dragged to safety by one of the others. Help duly arrived, and, unable to move, I watched with hilarity as endless swarms of zombies kept aborting any attempts to pull us up, until just enough space was cleared before the next onslaught to haul us both up.

It's bloody hard. I don't know what difficulty it was set to, but I didn't see a single group reach the chopper all afternoon. But what a rush.

And that's your lot for now. Valve is promising further substantial reveals of game content in the run-up to launch, in addition to a multiplayer demo that will be made available pre-release. Based on this playthrough, it's more of the same with some neat additions. Which is, again, in no way a bad thing.

The subtleties and depths added by the inclusion of melee weapons, a reworked AI director and so on, won't be fully appreciated until the final game hits. And so, the exasperation of a large number of L4D fans aggrieved that this is being sold as a separate game rather than released as an add-on is likely to continue until people experience it first hand.

The Charger, a ferocious new enemy. All those one-armed press-ups paid off in the end, then.

Valve simply urges fans to "trust" it; and in fairness the studio hardly has a history of unjustly mugging customers. The various pledges of ongoing support for the original may also prove an emollient, once they materialise (and Faliszek also teases that we haven't seen the last of the original crew: "We love those four, we love their story, but we think there's some other place to go as well. They're not dead, they're still going on. So definitely... We'll see what happens in the future.")