You probably read the title of this article and, like me initially, didn't see why this was a big deal. It's not like the N64DD was a secret project. The thing was released in Japan and flopped after only a couple months in stores...never to see a U.S. release.
Here's where things get crazy.
Youtuber Metal Jesus happened to come across one in Seattle, and after some observation discovered it was a retail version for the American market! What's crazier, is that it was made in 1996, 3 years before the Japanese model would go to market!
The whole experience leads the video down a rabbit hole that leads to a conversation with the developer who actually coded the exact system Metal Jesus has in his video. It's worth a watch to learn more about, although if you find yourself just waiting around to learn what's on that blue disc go ahead and turn it off. There's nothing on the disc.
Still cool to see a previously unseen and almost forgotten piece of gaming history.