I would estimate that Steam's numbers to be a lot lower then people imagine.
A couple weeks ago during the 75% off L4D, they announced that their weekend sale beat their launch sale by 3000%!!
An increase of 3000% wouldn't be possible unless the launch numbers are extremely small. For example if they sold 1,000,000 during the weekend sale then a 3000% would mean a launch sale of approx. 33,000.
Also, looking at the stats per game - L4D peaked at 24k yesterday..
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