HexJam HD is a Hayden-Wicki Jammer style concertina with hexagonal layout for the iPad.
HexJam HD emulates Concertinas, also called squeezeboxes, which sound like a reed organ or a small accordion. The left and right hands have their own mirror image 52-button keyboards. Each side has an identical 3 1/2 octave range.
Just press the buttons that coincide to specific notes and press buttons simultaneously for chords. At first this instrument may seem a bit alien, but if you try it longer you will find that the scale patterns are intuitive, also the built-in note guide makes it easier to understand the mechanics and start making music.