IMPORTANT NOTE: This article is for Arduino IDE version 1.6.6 (or above). To add a USB Game Controller to an Arduino Leonardo or Micro using Arduino IDE version 1.6.5 (or below) see the following Instructable: Add USB Game Controller to Arduino Leonardo/Micro.
Out of the box the Arduino Leonardo and the Arduino Micro appear to the host computer as a generic keyboard and mouse. This article discusses how the Arduino Leonardo and the Arduino Micro can also appear as a generic Game Controller or Joystick. This project will only work with Arduino products based on the ATmega32u4 microcontroller (i.e. the Arduino Leonardo and the Arduino Micro). It will not work with the Arduino UNO, because it is based on the ATmega328 microcontroller.
The Arduino Joystick Library (a.k.a. Game Controller library) used in the Instructable provides the following:
The latest version of the Arduino library that allows the Arduino Leonardo and Micro to appear as a Game Controller can be downloaded from the following GitHub repository:
This GitHub repository actually contains three different versions of the Arduino Joystick Library:
Copy the Joystick (and/or Joystick2 and/or Joystick3) folder from GitHub to the Arduino Libraries folder (typically located at %userprofile%\Documents\Arduino\libraries). The library (or libraries) should now appear in the Arduino IDE list of libraries.