Not content with talking to them about TF2 maps during a recent visit, Valve has gone blathering to Shacknews about Left 4 Dead's release date, which is now "late summer". Presumably on both PC and Xbox 360, for which it's been announced.

Still, Left 4 Dead will be amazing whenever it comes out. We've played it in Valve's offices and at QuakeCon, and it's one of the most enjoyable takes on co-op we've ever experienced.

In case you're not keeping up, Left 4 Dead sees four player-controlled "survivors" fighting their way through various scenarios to an extraction point, beset on all sides by zombies ("Infected") and their deadly bosses.

Thanks to AI developed by Valve's recently acquired chums at Turtle Rock, no two trips through an episode of the game are the same, as enemy resistance changes in intensity from bit to bit depending on what kind of an experience an "AI director" is trying to craft. Fortunately there will be natural periods of relief built in to stop you going mad.

Another wicked thing about Left 4 Dead is that another four players can take control of Infected bosses. These mentalists each have special powers (one lightning-fast boss has a prehensile tongue with which to lynch you from rooftops), and thanks to Predator-esque tracking vision can position themselves creatively for ambushes.

And there are lots of other wicked things - preparing defences (like petrol canisters) and fending off waves of zombies at the extraction point, saving your team-mate from a zombie death with a shotgun and then turning to him and saying "I like to keep this handy for close encounters", and of course knocking Kristan off a rooftop into chasing zombies.

Oh, it's just lovely. We hope to see some more of it soon.

(www.eurogamer.net)