The Ergonomics of Controllers
Rahul Choudhury writes "Over the years, the controller device we use as our extra limb into the world of gaming has evolved from joystick to d-pad, analogue control, and touchscreen. Gamingredients investigated the pros and cons of a variety of controllers from Colecovision to Xbox (and expressed their scores in flavours of coffee)."
This site shows a speculated tree of evolution of game controllers.
It is indeed evolutionary, with each generation resembling the previous one, but a bit different.
^_^