This is great! Combining shapes makes for a really interesting puzzle design space and it's definitely a neat riff on traditional sokabonning.
Not sure if you're going to develop it further (I hope so :-) ) but if you do, some of the interactions feel slightly counter-intuitive at the moment. For instance, there may be a better way to communicate (or to introduce) that lines are only pushable from sides you can touch. And some of the interactions in the third level felt a bit weird, especially when a yellow square seemed to jump over a blue line.