How to Emulate an Xbox Controller with Arduino (XInput) - Parts Not Included
DIY Arduino Buttonbox | Page 5
Programming Ponderings: Arduino Joystick Library
Create a Joystick Using the Arduino Joystick Library 2.0 : 12 Steps (with Pictures) - Instructables
Precision USB Joystick Controller BU0836
I made a gaming control panel using an Arduino Leonardo to play simulators. Currently using it for DCS World, but it should work in most games just like any joystick / gamepad.