Hop into the DSiWare Shop or the 3DS eShop right now and you'll be able to download The Legend of Zelda: Four Swords Anniversary Edition for free. Nintendo went beyond offering a simple rerelease by adding some neat features in Anniversary Edition.
For starters, Anniversary Edition introduces a new single player mode where you can switch between two Links to complete the adventure. If that wasn't awesome enough, Anniversary Edition also has new areas based on the original NES Legend of Zelda, Link's Awakening, and A Link to the Past. These levels will have the proper visuals native to their respective title.
The Legend of Zelda: Four Swords Anniversary Edition will be available as a free download until February 20, 2012. After February 20, it will become a paid download.