This was extremely fun, cleared all levels. The only part where I got stuck for a while is level 11 because I didn't realize you could move the grey blocks. I think it would be better for them to be unmovable obstacles. Also if you ever plan on making this into a bigger game, I recommend removing unnecessary blocks as much as possible for the harder levels.
I don't think the theme of the jam is represented that well because you have a lot of control of how things are going to turn out by understanding the rules of the game. But as a puzzle lover it's still one of my favorites so far, great job!