If classic Atari controllers are what you look for in retro games, and you don’t mind emulating the software, this Arduino build is what you need.
Created by South African YouTube channel Build It, the Arduino Atari Adaptor (or “The 3 As”) is a compact build designed to connect the 2600 joystick to any computer with a USB port.
The core of the project is an Arduino Pro Micro thanks to the fact that it shows up as an input once plugged into a PC. Connected to this are the correct pins for the controller, and the build is housed in a small 3D printed case.
After making the case look a bit more authentic, it connects over USB and acts more as a pass through for the joystick.
It looks like most of the effort in this project actually went into the original joystick, more so than the Arduino part. The one here was torn down, cleaned, analysed to work out the correct button inputs, and then resembled.
Luckily the diagram of these inputs, together with the code and a full guide to replicate this project, is available on Hackster.io.
If you don’t have the time or inclination to buy your own, they are being sold as a completed project. No price is provided but you can email the address found in the YouTube description to see how much it will run you.