Nintendo will give away Legend of Zelda: Four Swords free via the DSiWare store next month as part of the Legend of Zelda 25th year anniversary celebrations. As detailed at E3, the DSiWare version will be a remake of the GBA Four Swords game that came on the same cart as Zelda: A Link to the Past. It's a four-player co-op game that sees Link split in four using the Four Sword and set out to rescue Princess Zelda once again.
Those who played the GBA original remember its mint co-op gameplay mechanics that forced players to work together in tandem to overcome puzzles and sweet boss fights.
Nintendo makes no mention of online play, so our guess is it'll support local wireless play only.
You will be able to download the game for free some time "in September" via the DSiWare store via a DSi or DSi XL, or from the eShop store via a 3DS.