This is a very lovely and peaceful game! I feel like it would be something I would want to site in a cool dark room and relax while playing this. The colourfulness and sound reminds me to some degree of Flow.
Few suggestions:
1) The mouse movement was a bit strange for me and would prefer it to feel differently
2) The first "level" was a bit slow, I think you could shorten it up just a little bit and still give lots to the player. Until I got into the cave I wasn't as interested, but became even more interested and found it more enjoyable once I was climbing the mushrooms!
3) A quick description of what the orbs mean. It took me just before the cave to figure it out.
4) Maybe instead of orbs, what if the level elements acted as the orbs themselves. Not exactly sure how, but would help bring even more life to the levels, keeping the following feeling fresh and interact.
Great job!