A issue i see is that the Game field seems to be cut, not sure if its a problem of the WebGL Version, or Browser. but at a certain level i couldn't continue playing.
Talking about Playing
Really Cool Concept and nice to play and spend time for it. You should give it a chance for Mobile Section. I Think it can Trigger some people to Spend a long time on those Levels.
Audio, yeah fine some Casual Background Music could be interesting.
Cool little Game, keep up the great work.