Great game, really cool concept. I really like the different little puzzles you came up with. I also like how you introduced the tools one after the other.
I'm not sure if I got to the end though, after level 4 I was back in the level select area and only had level 1 to choose. And then after beating level 2 again i got a grey screen and couldn't continue.
All in all really fun game, well done!