Unfortunately I had to restart Chrome for an update and I lost my progression. I sent the link to a friend and maybe I'll be able to help him if he's also stuck there.
I love puzzle games, and this one was perfect! No repetition of mechanics, gotchas that bring a smile, and eurekas that provide satisfaction. The levels were perfectly designed.
Only the last one (?), next to the start, was too difficult for me, is it even possible?