Nintendo is celebrating the 25th anniversary of the Zelda franchise in a number of ways: an upcoming Wii release (Skyward Sword), free soundtrack CDs, and even a concert. There's even a free game, if you go to the Nintendo eShop with your Nintendo DSi or 3DS system.

The Legend of Zelda: Four Swords Anniversary Edition will be available as a free DSiWare download beginning September 28th. However, don't dilly dally--the offer is valid only until February, 2012.

Like the original Four Swords, the game allows four players to play cooperatively. Unlike the original, multiplayer is handled wirelessly--so there's no need to bust out those Game Boy Link Cables. In addition, the game has been updated with a brand new single-player mode. "Once players finish the main quest, they will unlock new stages and abilities to expand the game’s replay value," Nintendo notes.

In addition to the free Anniversary Edition, Nintendo is promoting its download services with two limited edition prepaid cards: one for the eShop, which can be used on the 3DS, and another which has Nintendo Points, which can be used on the DSi or Wii. Both will be available starting October 3rd, and will be available for $20 each.