In keeping with my "winging-it-by-googling-it" approach to app development, I've taken the game mechanics from the free Roller Ball game to make the experience somewhat goal-oriented. This basically means that you now have to collect 6 spinning cubes throughout each level before you can move on to the next level. I figured this would encourage full exploration of the space while also giving the player a sense of completion.
For now, I'm working on an Android version (with Google Cardboard support) and a standard PC version. There is also an Oculus Rift version - wow, this piece of equipment is awesome - and it's all going to be available at the same time; around about when I release the actual book in January 2015.