To start with, they had to rely on a high-resolution camera mounted on a frame, and a series of filters attached to a rotatingwheel, to create a set of single-frequency images from the same perspective, in order that they could be merged as desired.
The old rotating navigation wheel from the original iPod is gone, replaced instead by a solid-state wheel that works in much the same way, but doesn't physically rotate.
We never really found ourselves using the thumb wheel in our first-person shooters, but you can think of it as a two-way rotating programmable button if you will, and it spins in small enough increments to find use as a weapon or ability switcher.