Create a Joystick Using the Arduino Joystick Library 2.0 : 12 Steps (with Pictures) - Instructables
Add USB Game Controller to Arduino Leonardo/Micro : 9 Steps - Instructables
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.
HALJIA Joystick Tastenblock Schilderweiterung Spieljoystick Simulationstastatur und Mausfunktion Kompatibel mit Arduino Nrf24l01 5110 LCD I2c IIC: Amazon.de: Computer & Zubehör
Joystick Modul mit Arduino auslesen | Roboter-Bausatz.de