Sorcery!
As a long time fan of the 'Fighting Fantasy' series of choose your own adventures I had to flag this up. An app that immerses you in a world, much like the revered series, ​but with atmospheric graphics and music. Imagine using this with your class on the IWB! I'm going to try it out and see how it goes!
Even if you've read the cult classic Sorcery! gamebooks, you've never experienced a story like this. Developed by British indie studio inkle, Steve Jackson's Sorcery! for iOS is a brand new type of game that merges an epic fantasy plotline with an incredible amount of player choice.