So I got my hands on a raspberry pi zero this week and for the first project I decided to try and hack it into a nes controller.
I didn't want to hack the controller with holes, so I decided to redraw and 3d print the back part of the controller (in a new red raspberry color :p).
The image is loaded with RetroPie and is configured with the NES emulator and some roms.
The nes controller is wired directly to the gpio and I'm using the gamecon_gpio_rpi driver so the nes controller shows up as a joystick.
There were a few tweaks that had to be done to get it working properly, but all in all a relatively easy build. The NES games run great on the pi zero.
It's still a regular pi (zero) and the usb port is still accessible. This means I can still just hookup a wifi dongle/memory stick/etc and use it as a regular pi (zero). I'm sure this will double as a robot controller in the future. I didn't need a hub for the wifi, it runs fine with the wifi dongle directly connected (via otg cable).
For now it's a fun on the go gaming device. Find a tv, add power and your up and running. I can upload the stl (for the back part) somewhere if anybody is interested in building their own.