Metroid: Samus Returns for the Nintendo 3DS was announced during the first Nintendo Treehouse Live presentation at E3. It is a remake of the 1991 Game Boy game Metroid II: Return of Samus. While the game features 3D models and cutscenes, gameplay will still be in 2D classic side-scroller. The game was co-developed by MercurySteam, the team behind recent Castlevania games such as Castlevania: Lords of Shadow - Mirror of Fate and Castlevania: Lords of Shadow 2. This completes the metroidvania circle. It will be released on September 15, 2017.
In addition, a Limited Edition bundle and two associated amiibos were also unveiled during the reveal. The new Metroid amiibo is unique that it has a squishy texture while the new Samus Aran amiibo is shown striking her iconic pose from the game. Both the Zero Suit Samus and classic Samus amiibo from the Super Smash Bros. line will also have special functionality in the game but these features will be revealed at a later date.
This announcement is even more interesting considering that Nintendo recently shutdown fan project AM2R (Another Metroid 2 Remake) almost a year ago. The aforementioned fan game was also a Metroid II remake with colors and visual style similar to Metroid: Zero Mission.
For more information on future 3DS titles, you can also check the Upcoming 3DS Games page.
Source: Nintendo Treehouse Live at E3