OnTheGo Piano is is a project for the Alt Ctrl game jam. The point was to build a game and a controller for it.
We went with a keyboard-based control and the OTG USB cable, which allows to connect it to a phone.
The controller is similar to Guitar Hero/Rock Band controllers, however this time it is a piano thing. The device provides a full octave, where the main notes and the minors are mapped on the same key and switched in the software.
The game was build in Unity and currently contains about 250 notes in 12 "songs". The more successful the player is the more difficult the game gets.