Metroid: Samus Returns is arguably one of the biggest 3DS games of 2017 and something a long time coming. Metroid II was one of the classics in the series that had never been given any sort of upgrade or attention outside of the initial release on the Game Boy.
A new amiibo based on a Metroid is launching alongside of the game, and it appears that if you want to play the difficulty mode “Fusion” you have to have that amiibo. The Metroid amiibo unlocks the “Fusion” difficulty when you complete the game, along with the suit that Samus wore in Metroid Fusion. The amiibo also tells you the locations of nearby Metroids, so it might be worth checking out regardless of whether you want this suit or not.