I was really enjoying this. The puzzles are actually pretty challenging and really satisfying to finally get them.
But I finally got completely stuck on level 36 - I couldn't find any way to move anything in a way to even get started. So I went to refresh my browser to see if anyone was talking about that level in the comments. Hit Ctrl+R.... and completely reset my progress instead of refreshing the page. Rough choice of shortcut key there. I notice that's not documented so maybe it's a default part of the engine being used? In any case, I don't know if I can be bothered going back through the first 35 levels again. But good game and enjoyable puzzles until that happened.