Is there a way to lock a Navigation button to a level until a previous level has been completed. Angry birds style? Thanks. ==> To top it off, it would also be good to have a separate score system for each world. ==> Additional on world lock: I think this should be an option especially with the stage clear preset. It doesn't make sense for a stage clear game with all the stages unlocked from the start right? It can be used say, locked worlds which can be unlocked by completing a previous world/level, by purchasing with coins, or by in app purchase.