The "Legend of Zelda" watch is a multi-purpose device made by Nelsonic Industries, who obtained the Nintendo license back at the end of the 1980s. According to the Wikipedia, 12 million copies were sold, which is quite impressive and perhaps better than recent watch computers.
Is that a smartwatch? That's maybe not the main point here, but it's intriguing to think about the fact that there's already a lot of examples (like this) of showing how computation can help triggering a playful user experience on a wrist-based tiny device.
Beyond the functionalities, I'm also curious of the gestural behavior of the user here. The manipulation of the buttons is tricky but doable, although it's way different than the NES version of Zelda.