PowerPlay5

This app is a unique MIDI controller, and fun to play, but there are three concepts to understand first.
Concept 1 - POWER CHORDS - There is a musical chord, called a power chord, usually associated with guitar playing. Think of yourself as a guitar player on stage, but instead of holding a guitar you're moving around while holding an iPhone.
Concept 2 - MIDI CONTROLLER - PowerPlay5 is a midi controller app. It doesn't create any sound on its own. Instead it tells another app which notes to play. The other app (a synthesizer app) then creates the sound of the chord being played.
Concept 3 - THE SETUP - Usually you will open the synthesizer app first, choose a sound, and then make sure "Background Audio" is on. After that, open PowerPlay5 and start playing. (Note that some synthesizer apps also require a MIDI bridge app. See the instructions at the support website for more information.)
This app is interesting because you play chords by aiming the iPhone in different directions while tapping with your thumb on the screen. It's almost like a form of choreography. Learning what direction to aim the phone to get the chord you want next is part of the fun of playing.
The best way to understand where all the chords are is to look at the instructions pdf found at the support website.