I'm forwarding the pictures over here to see if anyone can figure out what this might be. This came from a FB group I'm following, the poster of these pics is not a registered user of the forums that I know of so I have not included his name.
"Ok listen to this story!!! I have a listing on Craigslist that I collect video games. So I get a call lastnight from this older guy (69 years old) we get to talking and he tells me he use to work for sega in the mid 80's. He says sega was working on a project that was later canceled they though away all the carts but he saved one he thinks this is the only one left in the world. So he sent me pics of it to see if I knew anything about it if I thought it was worth anything. Well I have no clue what it is my guess is it's for a master system from the square look of it. Anyway if anyone knows anything about this please share."
Now this is outta Louisiana and I'm way way up north so I don't know much more than this. I'm gonna post the pics of this cart, and Tempest or anyone else can tell me if this is something new or not -- it has not been plugged into a 2600.