Ok. A month or so's work and I've managed to completely redesign Rebound into something new: Tumball. This was done because the original graphical style apparently didn't appeal to a wide range of people. In addition the app now has a small story line: The Tumballs have lost their water and you have to get it back!
Some of the mechanics have changed slightly and the game has been tweaked to make things clearer and more fun. The contrast has been increase to make it easier to play and more personality has been put into the visuals. There's a better rewards system and it's more fun!
The levels have been revamped, mostly the last few. Hopefully this will make it better to play. I will be uploading a demo shortly.