Description

Select a key/mode. From there tap each button to hear the chord. Pick a chord to modulate by tapping the Pivot button. A new key/mode will be presented below the existing one. 

Use it as an idea song scratchpad. For example, select C Major, tap C/F/G for the typical 1-4-5 progression. Then maybe you decide that you want to modulate to a new scale on the 5. Tap the Pivot button over the G, and a scale will be randomly generated for you. For example, F# Phrygian, which has G in the second position. From here you could do something like a 2-4-5 progression.

Some knowledge of progressions is useful, but you can always to play around by ear (after all if it sounds good it is good!)