Left 4 Dead has been hanging around the charts for months now, like a...well, like a zombie hanging around a shopping mall. But how many copies has it sold in that time?

Speaking today at GDC, Valve revealed that it's sold 2.5 million copies at retail. Note, that's at retail. So GameStop, Amazon, that kind of thing. It does not include sales figures for Valve's own Steam service (which are top secret), so really, the number will probably be much, much higher.

Still. They're just the icing on the cake. 2.5 million is impressive enough on its own.

Left 4 Dead Hits 2.5 Million Sold at Retail [Shacknews]

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