Inflation is the main problem, and will kill your app if your math is off. When people run out of coins, they spend real money to get more. However, let's say y

Inflation is the main problem, and will kill your app if your math is off. When people run out of coins, they spend real money to get more. However, let's say you have a broken game that pays back 150%, because you didn't get your math right. Your player coin balances suddenly start climbing, and your revenue dries up. This is bad, because even once you fix the broken game, you may need to introduce money sinks to try to get things back under control. Installs are regular ads, just like any other mobile game. You pay Google, Apple, Facebook, etc. Facebook Canvas used to be a big source of revenue, but most people have drifted over to mobile. Demographics are female, 35+, so these are not early tech adopters.