The mobile gaming market in North America continues to grow. As of Q3 2014, there are 141.9MM NA mobile gamers, up from 111.3MM NA mobile gamersin 2013. These mobile gamers spent an average of $32.65 in the last year,generating $4.63B in NA mobile gaming revenue.
The graph below provides a view of how gamers discover games (click on it to get a larger view)
For a great analysis please see this free report.