There’s a good chance that the future of Nintendo will depend on how well its push into the mobile market goes, so it’s good to hear that the company’s first mobile app has been really successful so far. Known as Miitomo, the app has been downloaded 2.6 million times in the last week, according to a report from SurveyMonkey on Monday, and has already managed to accumulate more than 4 million active users since it was released at the end of March.