Yep. "A service launching this week will tell you that Machine Zone is currently spending somewhere around $12 per user with AdColony, InMobi, and Unity Ads, u

Yep. "A service launching this week will tell you that Machine Zone is currently spending somewhere around $12 per user with AdColony, InMobi, and Unity Ads, up to $20 per user with Vungle, and between $2 and $30 per user with Chartboost." http://venturebeat.com/2015/08/12/this-service-tells-you-what-supercell-machine-zone-and-other-big-publishers-spend-on-user-acquisition/ http://venturebeat.com/2015/08/12/this-service-tells-you-wha... GoW has very low retention. Users who stick around in GoW are the kind of people who like to spend a lot of money to feel empowered. But, finding and keeping those people is very expensive because it involves churning through a whole lot of users who aren't like that.