The RetroGen adapter is an unofficial adapter that lets you play Sega Genesis/MegaDrive games on your SNES. In reality its a Sega Genesis on a chip, only using the power and controller of the SNES, it uses it's own port and comes with AV cables to plug into your television.
Overview
The RetroGen was made by RetroBit, it's purpose is that it allows you to play Sega Genesis games on your Super Nintendo Entertainment System. The cartridge adapter is region free.