Kind of cool. I've got one of these I picked up at a thrift for a couple bucks and works alright, it's a Beeshu product like the zipper or that joystick they made. Never seen a NOS one though, I'd say it's worth at least $30 to the right person though.
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"Rocky and Bullwinkle is the worst unlicensed NES game I can think of. Even Color a Dinosaur is better, and it just involves coloring a dinosaur."