OK I mean real adults :) The same demographics who you would imagine as a typical reader of Agatha Christie or Tom Clancy, football or horse race enjoyer in the era before computer games and internet
I think the idea that thriller novels or horse racing are more mature than video games questionable, however. Your average adult thriller (or hollywood AAA movie) has a plot that would sit right alongside video game plots.
Most of today's gaming industry is targeting adults. Kids rarely have the money to purchase 70$ games more than once or twice a year.