In this skill game it is the goal to bring a ball on the inside of a larger shell to the finish. You move the ball by moving the shell. Tilting or rotating the iPhone or iPad tilts the surface and the shell starts to roll. The small ball on the inside moves accordingly through gravitation.
In order to manoeuvre the small ball, it requires a steady hand and some patience.
It begins fairly simple, but with each level new challenges are added:
Geometries that have to be overcome, holes that need to be avoided and catapults that shoot off the balls.
Due to usage of the latest graphics programming interface Metal this game requires Apple A7, A8, and A9 GPUs which are built in iPhone 5S and newer iPhones and newer iPads.
However, good performance is only achieved from the A8 chip and higher.