Valve’s Left 4 Dead 2 has sold over two million copies in its first two weeks of availability.

In doing so, the multiplayer-focused zombie shooter doubled the sales total achieved by 2008’s Left 4 Dead during the same timeframe, according to the developer.

Released on November 17 for Xbox 360 and PC, Left 4 Dead 2 was backed with a $25 million marketing campaign that helped generate record pre-orders for the title, leading Valve to predict that it would become the company’s fastest-selling product in history.

"Left 4 Dead 2 is off to a great start with strong support at retail and great reviews from the press," said Doug Lombardi, Valve’s vice president of marketing. "Meanwhile the title has already been played by over one million Xbox Live Gold account holders, and news regarding L4D2 DLC 1 is coming very soon."

Read our Left 4 Dead 2 review.