Nintendo's first smartphone game is launching this week in the US

After being released in Japan earlier this month, Nintendo's first smartphone game, "MiiTomo", is coming to the US on March 31st.

It will be released on both iOS and Android, and will also be available in the EU.

Part game, part social media platform, the game's hook revolves around creating a "Mii" avatar using your smartphone's front facing camera, and then answering questions that can be seen and favorited by your friends. Emphasis is placed on customizing your character, which is why the game is labeled "free to start", the term Nintendo has been using to mean featuring microtransactions.

If this sounds somewhat familiar, you probably remember when Nintendo first debuted the concept of Mii avatars with the launch of the Nintendo Wii game console back in 2006.

MiiTomo is the first product to come out of Nintendo's partnership with the mobile publisher DeNA, which was announced last year, and will be the first of five titles to be released between now and March of next year.

In addition to being Nintendo's first game to appear on a non-Nintendo platform since the early 1990's, MiiTomo is notable for requiring a Twitter or Facebook account to add friends, unless they're in the same room. Both social networks require you to be 13 to sign up, meaning Nintendo's target demographic may skew a little older than usual, though age reinforcement can be difficult to enforce. It could also represent a change of heart from the company, who traditionally require inputting a complicated "friend code" to link up with friends for cooperative play on the 3DS and WiiU.

The game's launch in Japan was met with immediate success, reaching the No. 1 spot in the App Store and has been downloaded one million times since becoming available. The Japanese launch coincided with the release of a trailer for the game for U.S. audiences, which provides more insight into the game's mechanics and overall gameplay.