The Mega Duck (also known as the Cougar Boy in South American countries) was a handled similar to the Supervision in the way it was trying to compete with sales of the Game Boy. It was created in Hong Kong and released in various parts of Europe and South America.
Most of the games were developed by the Chinese game company "Sachen" who were infamous for making unlicensed NES games.
When the Mega Duck failed to sell as many consoles as the Game Boy, Sachen released ports of their games onto unlicensed multicartridges for the Game Boy sometime after.
Like many of the obscure systems out there, MESS is the most well known emulator available for systems that barely have any emulation support.