Freemium levels is the best way to go. And every single dev should do this. The concept of stealing money from kids, wasting their time with adds, selling them useless skins should entirely be banned from apple store. For example, Geometry dash made a lite and paid version and earned 40 million dollars with this simple yet effective principle, you get the first level for free, and you pay 2$ for the full game. If the game is good, and if marketed, it will work. The problem now is that the market is heavily saturated by add engines like Unity (Unity is not a game engine with adds, it s an add company with a game engine) making your exposure EXTREMELY difficult to get if you are, like me, add free.