S.Peelman on 28 December 2015
Yeah that's their official piece of artwork for the game. They made one of these posters for every game, sadly we've yet to see one for Zelda U. 
EDIT: I've had the tall version of the one in the second post as a vertical scrolling screensaver. Awesome stuff. Also seen a timelapse on youtube once of the creator drawing it in photoshop. Impressive stuff.
