The app it's self is wonderful, but there could be some changes made to make it perfect. For instance, to unlock a secret level make it so the person has to wait a certain amount of time or can instantly unlock the level by paying the coins. Another thing, make the story line less predictable. I, being someone that reads a lot of books, love a plot with twists that keep me guessing. Last but definitely not least, please consider making the characters customizable, so the player, of the game, can feel like they are, more, of a part of the storyline.