Valve really, really wants you to play Left 4 Dead 2

If you're one of the five people left on the planet that hasn't heard of Left 4 Dead 2, Valve is launching a $25 million advertising blitz to make sure that you do.

Valve President Gabe Newell says, based on the strength of pre-orders, that Left 4 Dead 2 is expected to be the fastest-selling product in Valve's history. The sequel will arrive on the PC and Xbox 360 this November.

As if that weren't enough zombie-infested goodness for you, Microsoft also announced today that the original Left 4 Dead will soon be joining the Xbox 360's Platinum Hits collection.