Nintendo's first big foray into mobile gaming, Miitomo, boasts 10 million downloads, but it's more than a game -- it's a quasi social network that's apparently turning into a ghost town. It's generally understood that games see a big bump in players at the outset and gradually that number declines over time. For social networks, where the typical "gameplay," so to speak, is interacting with others, once the user-base declines, there isn't much else you can do. Just ask whoever is still on Ello. The folks at the SurveyMonkey Intelligence blog have been keeping an eye on Miitomo and have made some sobering observations on how Nintendo's smartphone app has performed since launch.