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We must take into account that the Witcher was released for a temporally low price and also that The Witcher 2 give some goodies with the preordered version, this may have boosted both of them to the top bestselling tiles. But even with this two favorable factors I think these are great numbers.
Yeah. Remove those games that are / were free and Witcher 1 is #10 and Witcher 2 is #11

And it's amazing how many RPG titles are in the top 20.