Nice visuals. 

On my first run i collected all flowers. Not apparent it damaged me until dead.
On my second run i collected the big square and crashed the game :p

Not sure if intended or a technical issue, but the timing is off.  You get punished for being too on beat and has to practice to delay your actions, which does not make sense for me. Would probably give a nicer feel if the window is like 0.0s-0.3s, instead of 0.3s-0.6s or whatever you got set up.

Managed to completed it XD

I get the mechanic but kinda hard to time it

maybe instead of sudden white bar, you could just add gradual stage of change to the bar

so the player can kinda get a visual feedback when is the time to press it

Didn't quite got the gameplay. Music was good, but rhis mechanic when I suppose you need to click in the beat to jump higher, but it doesn't work most of the time - well, needs some attention. Overall - nice experience. Looks like big games such as super meat boy and etc.

A great idea for how you implemented the theme! The game is fun, and I really like the art style.

the colours (atleast on web) hurts my eyes