for mobile games, however its performance limits led to the adoption of various native binary formats for more sophisticated games. Due to its ease of porting between mobile operating systems and extensive developer community, Unity is one of the most widely used engines used by modern mobile games. Apple provide a number of proprietary technologies (such as Metal) intended to allow developers to make more effective use of their hardware in iOS-native games. Monetization With the introduction of the iOS App Store and support for in-app purchases by October 2009, the methods through which mobile games earn revenue have diverged significantly away from traditional game models on consoles or computers. Since 2009, a number of models have developed, and a mobile game developer/publisher may use one or a combination of these models to make revenue. Premium The premium model is akin to the traditional model where the user pays for the full game upfront. Additional downloadable content may be available which can be purchased separately. Initial games released to the App Store before in-app purchases were available used this approach, and still common for many types of games. Freemium The freemium or "free to try" model offers a small portion of the game for free, comparable to a game demo. After completing this, the player is given the option to make a one-time in-app purchase to unlock the rest of the game. Early games shortly after the introduction of the in-app purchase feature used this approach such as Cut the Rope and Fruit Ninja. Free-to-play A free-to-play game requires no cost at all to play, and generally is designed to be playable from start to finish without having to spend any money into the game. However, the game will include gameplay mechanics which may slow progress towards completing the game. Commonly in mobile games, this is some form of energy or stamina that limits how many turns or actions a player can take each day. By using in-app purchases, the player can immediately restore their energy or stamina and continue on. In-app purchases can also be used to buy power-ups and other items to give the player a limited-time advantage to help complete the game. While free-to-play games had been common on computers prior to mobile, the method was popularized in mobile gaming with Candy Crush Saga and Puzzle & Dragons. Advertising-supported A ad-supported game will be free to download