The SNES controller adds two additional face buttons (X and Y), as well as two shoulder buttons, to the NES iteration.
Image credit: Alphathon (alphathon.deviantart.com)
To download this Add-On, we highly recommend you do it via the user interface in Kodi. Simply look for the "Get More" button in the Add-Ons menu. If you want to install it manually, you can direct download the zip below then in Kodi, look for the "Install via Zip" option.