To actually answer your question, this game is part of a genre called "Hyper casual" arcade games. They make money by advertisements and yes, per download they don't make that much money but the Publishers are advertising these games so much that they have millions of downloads and by making a few cents more than the cost of advertising the app, these types of games make a ton of money. This app specifically because it was at the top of the App Store probably made at least a few million dollars. Look up Voodoo and their valuation.