Social games attract tens of millions of players on Facebook and other networks, but compared with traditional PC and console-based games, they make a lot less money, a challenge impeding the genre’s growth. While millions of “hardcore” gamers willingly pay $60 per title and $15 in monthly subscriptions for an MMO like World of Warcraft, the average monthly revenue per user for even the biggest social games is estimated to be $1 to $2 .