Looks like an interesting idea, but I have no cue about music to help you.<p>Anyway, anecdote time: My wife used to play random chords in the guitar. She explained me that if you follow some rules it would sound good. I don't remember the details, something like<p>X -> Y or Z<p>Y -> X or W<p>Z -> X<p>W -> X or Y<p>where X, Y, Z, W are actually A, B, C, D, E, F or G, but I can't remember which ones. (Did I mention I don't play the guitar?)<p>So I made a program that played in the speaker 4 notes per chord, and followed those rules to select the next chord. It was surprisingly good for the low effort I made. It was not fantastic or groundbreaking, but not horrible at least.