The very first game in the Banjo-Kazooie series was simply called Banjo Kazooie. After the release of Banjo Kazooie we were introduced to a game called Banjo Kazooie: Grunty's Revenge, which never really caught on due to the fact that the game was made for the Gamebody Advance.

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Banjo Tooie released for the Nintendo 64 and was a highly anticipated game for fans of the Banjo Kazooie series.

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In 2005 Banjo Pilot was another title released for the Gameboy Advance.

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In 2008 we saw
Banjo Kazooie, Nuts & Bolts, which was a pretty disappointing release of the heroic duo Banjo and Kazooie. Fans who have waited years to see Banjo and Kazooie were introduced to a whole new element of game play. Vehicles were used in the release, which was a cool addition, but at the same time, they were overused, which took away the whole
'big adventure' aspect of the originals. The game was referred to as Banjo Threeie, till the actual title came in to play.
The confusing part about the rumored games release is its definite title. We did not see a Banjo Threeie title, but technically speaking, its already been made.
Banjo Fourie has also technically been made.
The new title that is rumored to be in development should really be called Banjo Sixie, but it won't be called Banjo Sixie. It is rumored to be called Banjo Fourie or Banjo-Kazooie 4, but at this stage it is anybody's guess. They could go back and actually give us a proper Banjo Threeie game title, which would be appreciated.