Some metrics of online game players

According to Media Metrix numbers from May of 2004, 257 million unique people visited game related web sites out of a total Internet audience of 531 million. In other words, 48.5% of all internet users are game players, spending an average of 16.3 minutes per usage day on games. 75% of all game players are over the age of 25,
with just 13% being under the age of 18. 52% of all game players have children, and 58% of all game players are female.

Source: http://www.gametrust.com/downloads/GTGuidelines.pdf