A few words about what I liked and what can better - first I had no clue I can jump in level one even, which is why I got stuck and was about to give up, before someone asked me if I tried every button - so per coincidence I found the jump button. No clue it was space. The hint bubble says "wasd" to move, which is obviously not true. Only, A and D, left click and space.
I got stuck in the first level with 2 tall x-blocks as well - again at the point of giving up. Then again found the solution myself after looking if I can found some hint in the internet - which I didn't.
My idea: Don't you think you can implement a hint system for players that can't figure out a solution by themselves? To prevent they close the game in frustration.
Word of praise:
You made a great little game with really fun mechanics, sound design and fantastic separation and melt back together behaviour! I loved the game :) !!
(Not including here the drawbacks I mentioned earlier)
Way to go! :) Hope my critic helps.