Nintendo has stormed onto mobile, and gamers are eating it up.

Miitomo, the publisher’s first smartphone app, is the No. 1 most downloaded game for iPhone and iPad in the United States, according to market-tracking firm Sensor Tower. The social app, which GamesBeat is enjoying, only came out this morning. That means it has rushed to the top of the charts in less than 24 hours. It took Miitomo about two days to do the same thing in Japan. This is more evidence that gamers are on their smart devices waiting for content from respected publishers like Nintendo, and that company — which is struggling with its traditional console business — stands to make a lot of money from a mobile industry worth $34.8 billion.

By reaching No. 1 in just a few hours, Sensor Tower estimates that the game could surpass 200,000 downloads on the iPhone alone after 24 hours, since that’s typically what the No. 1 app does on average. You can probably add around 20,000 to that for iPad. And that does not include Android, which could pile on a few hundred thousand more once we get up-to-date data for Google’s mobile platform.

Nintendo should feel good about this response. People clearly want to see what a smartphone app from the publisher is like, but it could turn that momentum into long-term success in the lucrative mobile space.

Update: Clarifying Sensor Tower estimations.