Fun and challenging...
...and incredibly frustrating at times. Like level 13, which was extremely hard at first - but after a good night's sleep, I found the ridiculously easy solution. I'm currently stuck in 16, but I'll get there someday!
You're really good at designing challenging levels and fully using the potential of a simple set of rules. I had previously observed this on Orbox B, the first of your games that I played. The graphics are perfectly ok. There could have been different music loops, but you can turn them off, so that's no problem.
The people who are writing reviews just to state that they're voting zero because the author is this or that, without any regard for the submission itself, are breaking the review guidelines. Everyone who's bored can have fun reporting them as abusive ^_^