“If someone tells you a rule, break it. That’s the only way things move forward.”
–Hans Zimmer
Isomorphic refers to different objects that have the same shape. In this case, the keyboard is isomorphic because the chords keep their shape when changing keys. This is different from a piano, where each major chord has a different shape. On an isomorphic keyboard, a major chord is always the same shape. One benefit of this is that you can easily visualize the relationship between notes. This is powerful because melody and harmony are based on the relationship between notes.
There are many isomorphic keyboard layouts. Pegboard uses a layout called the harmonic table. With this layout a step up to the right is a major third, and a step up to the left is a minor third. Western music theory is based on tertian harmony, or chords built by stacking thirds. Conveniently, this means this layout places the notes of a chord right next to each other. Major and minor chords are simply a triangle pointing right and left. Extended chords can be built on top of this and you only have to learn their shape once.
To the right of the keyboard is the scale inspector. Tap on the scale dropdown to choose from over 150 scales. The keyboard will highlight the notes of the selected scale. That way you can improvise without having to learn each scale individually. The tonic and octave parameters adjust both the keyboard and the pitch of the drone.
Scale highlighting is a powerful tool that allows you to see the structure of any scale. It can be used to find interesting modulations and pivot chords. It can also be used to find exotic scales that work in the current key.
Rock music popularized the use of the power chord. This is just a triad with an octave instead of a third. The top three most consonant intervals are unison, octave, and perfect fifth. This means the power chord is a very consonant harmonization. You can play power chords on the keyboard by playing a note and the note directly above it. Playing the octave is optional. Improvising with power chords can be a great way to develop a chord progression.