People who purchased an American 3DS, 2DS or 3DS XL can download this game before 2/2/2014 at 11:59 PST. You must have your NNID linked.
To celebrate The Legend of Zelda 25th Anniversary, Nintendo are offering The Legend of Zelda Four Swords Anniversary Edition as a free Nintendo DSiWare download, starting from September 28 2011 until