Directly to you from Twitter:
Get ready for a Bound Hero Battle with Alm and Celica from Fire Emblem Echoes. How strong is their bond? Play the m… twitter.com/i/web/status/8…—
Nintendo of America (@NintendoAmerica) July 06, 2017
…Wanna play? Buy a 3DS.
That being said, click on Fire Emblem Heroes for everything you need to know about the game. 😀