I am interested in demographics of people who actually play my game. Here are few assumptions I made:

 - Players, especially the younger ones, are often not the buyers (or downloaders in case of freemium) and I don't think I can get data about buyers anyway
 - Games targeted to a certain audience can be played by completely different group in the end (Pokemon vs. Call of Duty)

The closest I can get is to probably get a similar game that already has demographics data. But how did they get the data? 


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I have read the following questions:

 - http://gamedev.stackexchange.com/q/2064/30949
 - http://gamedev.stackexchange.com/q/32209/30949

These questions give me some data, but not the way how were the data obtained. Also some of the links are already invalid.