Even with heavy competition from Modern Warfare 2 and other highly anticipated fall 2009 titles, it looks like Left 4 Dead 2 will be highly successful for its developer Valve. Today the company announced that in its first two weeks the game has sold "over 2 million retail copies" worldwide which they claim is "more than double" the sales of the original title in their zombie co-op shooter series.

It's important to note that Valve stated that their sales numbers came from "retail copies" of the game. As usual Valve keeps sales of their games via their Steam service close to the vest. They also didn't state how many of the two million retail copies were of the PC version. In the meantime Valve says that news on the first Left 4 Dead 2 downloadable content will be "coming very soon." We think we have a good idea on what that content might be about.