Bounce has been a project that creator, John Allwine, has used to learn various aspects of programming. The first version was written in 2003, when John was in high school and was learning Java. It has its quirks but you can check out that version here.
The next version was written a few years later, when John was in college and was learning C/C++ and OpenGL. It started as a 2D simulation, just like the Java version, but evolved into a 3D version as he learned more about 3D rendering.
After that, John improved the look of his 3D version so he could include it on his demo reel when applying to Dreamworks Animation. After getting the job and working for Dreamworks for three years on movies such as How to Train Your Dragon, Megamind and Madagascar 3, he decided to try his hand at making iPhone/iPad apps. So Bounce was reborn!
The latest version is back to 2D and takes advantage of the multitouch and accelerometer capabilities of the iPhone and iPad, as well as adds a whole new look. Check it out!