Though it's structured more like an interactive picture book than an actual game, Petting Zoo is still an excellent and entertaining app for kids. It is available now for iOS, with an Android version coming in the next few weeks.
The app contains drawings, each of which constitutes as a chapter. However, there is no overall narrative story that takes place. Instead, it simply contains 21 of Niemann's hand-drawn animals that each react in different ways to five swipe movements (up, down, left, right, and center tap).