The classic parlour game with a twist, you can see how the computer is storing answers as you go along.
The idea is that you "teach" your iPhone how to play the game, and see how the data is stored in a binary tree.
Your iPhone (or iPad) learns from your answers and stored them on your phone, becoming more and more intelligent over time.
A wonderful education tool for learning about binary trees (look at the worksheet pack on www.studeapps.binarytrees) for full information about how this App helps you to learn about this important computer science concept.