A nicely done minimalistic game. However, I feel it is too mindless; at some point, I start to click randomly, and I pass the stages eventually. 

Also, I feel music and SFX could enhance the overall experience while maintaining the Zen value.

Felt quite elegant and calm, probably what my game should have been more like. Good job! 

I like how calm the game feels. Would work great as a casual mobile game. Well done!