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.
Arduino Joystick Module Example – 42 Bots
Arduino Robot With PS2 Controller (PlayStation 2 Joystick) - Hackster.io
Arduino-er: Arduino read Playstation 2 compatible Wireless Controller using Arduino-PS2X
PlayStation 2 Controller Arduino Library v1.0 « The Mind of Bill Porter
Arduino Joystick Shield
Arduino Joystick Project: joystick shield | x and y axis | joystick controller | 2 axis joystick - YouTube
Analog JoyStick with Arduino - Tutorials
Programming Ponderings: Arduino Joystick Library
Send physical gamepad input to two devices simultaneously via gamepad emulation - Project Guidance - Arduino Forum
Arduino UnoJoy gamepad (Windows, XBox emulation) - YouTube
Using Logitech Extreme 3D Pro joystick with Arduino HID library « Circuits@Home
How to Emulate an Xbox Controller with Arduino (XInput) - Parts Not Included
Ardunio Micro Joystick Card | The Sim
Programming Ponderings: Arduino Joystick Library - Version 2.0
Basic Arduino Based RC Controller Library - The RC Tractor Guy
Arduino UnoJoy gamepad (Windows, XBox emulation) - YouTube
Teensyduino: Using USB Joystick with Teensy on the Arduino IDE
GitHub - ricardoquesada/bluepad32-arduino: Bluepad32 for Arduino (mirror)