A new feature in the Mii Plaza tracks what you have and have not completed.
Upon installing the recent update to the Nintendo 3DS and visiting the Mii Plaza, players will be greeted by a bounty of new content to enjoy. Accomplishments, a new feature that tracks a players achievements is now available.
In the main selection screen of the Mii Plaza players can now select the Accomplishments category. Within this menu is a list of various different tasks players can complete. These vary from completing a puzzle swap panel to simply filling up your Mii Plaza's population. There are a total of 78 accomplishments, some bearing unknown requirements. These unknown accomplishments simply show a "???."