Very creative and interesting idea. I definitely think with some polishing of the controls and physics, this could be something pretty cool. Probably the hardest part of the controls to deal with (other than suffering by playing on trackpad) was that the metal ball would have more elasticity than I would have liked when hitting a wall, causing for example on level three to 'ride up' the wall rather than sinking straight down after hitting a wall. I like the idea of having a weightless anchor at the end of the chain, there's something there that could be really fun. In general, I think playing with the weight and impulse of the ball will make the game feel better.
Cool project!