I love this game, if only because of how many chances it gives you. It's quite a generous game. You can even fire rapidly! The music is also very stylish. It took me awhile to understand it, though. It is quite a creative idea. I guess there are other black and white games like this, though.
I even like the little sounds when the cannon fires. It is of course more complicated than it looks at first. Aren't all games? You seem to have an interesting perception of gravity. Contrast is just a cool word.