Four years after the game's release, a new game mode is unearthed. Dust off your Nintendo 64!
Well, who would have thought it? Turns out that after all these years, there was still something hiding in Banjo-Tooie. The secret is actually a new game mode called "Bottles' Revenge". In it, the evil spirit of Bottles the Mole follows the players throughout the world of Banjo-Tooie as they play. A second player can play counter-operatively to hinder Banjo's progress throughout the game by possessing various enemy characters whenever Banjo is close enough to them. Some enemies also have a taunt which can be used by pressing the L Button.
The hackers at The Rare Witch Project have managed to unearth this secret, and have posted a more detailed description of the mode on their site, along with pictures and a video of the two-player gameplay in progress. The only catch is that you'll need either a GameShark or an Action Replay for the Nintendo 64 to be able to access it, as there doesn't appear to be any normal way to unlock the mode -- at least, not yet. However, codes are listed for all four regions -- US, Japan, Europe and Australia, so there's no excuse for not checking this out if you have a GameShark or Action Replay.
The only other thing of note is that you can't control bosses using this mode - it only applies to drone characters. Devil Bottles will say "Looks like I'm not needed here!" and then disappear until the boss battle is over.