I enjoyed the free mode! The idea is great, and it gives a very relaxing experience. Walking randomly, then changing the tone or the key, gives some sweet harmonies. Yeah that's totally the kind of stuff that I enjoy! :) Plus, the visuals are nice.
I admit the puzzle mode confused me a bit. I didn't grasp what use is the metronom, and why making the right melody sometimes doesn't work. I've finally figured out that activating the metronom, then playing the melody works most of the time. But I'm not sure... Still, the concept is nice: sound, memory, and spatial puzzle... It has potential.
But honestly I'm mostly fan of the free mode.^^ Creating music with game interactions is always fun. And this game gives a nice way to toy with a sequencer! Great job.