A USB gamepad that neatly sits on top of the phone’s keyboard. Uses an ATMEGA with V-USB firmware to emulate a keyboard.
Original writeup
https://emerythacks.blogspot.com/2011/12/n900-gamepad.html
Featured on
https://www.engadget.com/2011/12/12/nokia-n900-gamepad-hack-dispenses-with-beauty-sidles-up-to-sore/
https://hackaday.com/2011/12/12/nokia-n900-control-pad-is-perfect-for-gaming-on-the-go/