Arduino Project: Commodore 64/Amiga, Atari 2600/XL/ST, ZX Spectrum Joystick to Windows/Linux (RetroPie) USB | jfrmilner's Tech Blog
How To Program The Pro Micro (atmega32u4) As A USB Gamepad Controller With Arduino - tinkerBOY
Arduino USB-Joystick | Ingmar's Retroblog
Arduino joystick - Geeetech Wiki
Teensyduino: Using USB Joystick with Teensy on the Arduino IDE
Tutorials On Arduino And Joystick Interface - Makerguides.com
Digital Joystick to USB Adapter (diy, cheap and easy) - English Amiga Board
Kevin Peat - Arduino USB Joystick
Amazon.com: SJ@JX Arcade Game Controller Button Microswitch 8 Way Joystick Zero Delay USB Encoder Cable Stick DIY Kit for PC MAME Retropie Raspberry Pi : Video Games
DIY Joystick Game Controller using Arduino Leonardo and Joystick Module