E3 2009: Microsoft press conference offers first look at sequel to Valve and Turtle Rock Studios' survival horror shooter, due this fall.

Last week, Valve offered a brief teaser announcement that it would be party to the 2009 Electronic Entertainment Expo, sparking waves of speculation as to what, exactly, the Half-Life 2 maker would have on hand to show. As part of Microsoft's E3 press conference today, the answer to that question surfaced when the publisher showed the first trailer for Left 4 Dead 2.

According to the brief trailer shown among a litany of other games arriving exclusively for Microsoft's platforms, Left 4 Dead 2 is expected to arrive on the Xbox 360 and PC on November 17. The brief trailer also showed survivors battling hordes zombies on a bridge, featuring the new chainsaw weapon.

As part of the 2009 Game Developers Conference in March, Valve said that the PC and Xbox 360 editions of the Turtle Rock Studios-developed Left 4 Dead have combined to sell more than 2.5 million units at retail worldwide. That number does not include sales through Valve's online distribution platform Steam, a statistic that the publisher traditionally keeps under its hat. However, Valve founder Gabe Newell revealed in February that during a one-weekend-only half-off sale through Steam, Left 4 Dead sales skyrocketed 3,000 percent.