Interesting concept, but I feel like without knowing what the enemies would do I mostly have to brute force my way through the levels. Don't get me wrong it's very satisfying once you reach the end, but until then it's a lot of trial and error which doesn't really make you feel like you deserve reaching the end. Especially when the levels get larger and larger. Mark has a video on that, I believe ;)
But all in all it feels at least like a complete game, despite the lack of music and sfx. So: good job on that!