Great concept, and I can really see what you were going for. I assume the goal was to make the bar at the bottom be in sync with the piano music, and if you would've achieved that, the game would be so incredibly intuitive. Right now it's difficult to match the dots on the bar, but given the timeframe it's completely understandable.
I actually do think that you have something here. If you flesh out the gameplay and artstyle a bit more (maybe towards the colourfullness of Geometry Wars), and have the synced music, it could be a great full game!