As we all know, Rare was once a second-party Nintendo studio but was purchased by Microsoft over a decade ago. When the acquisition took place, the UK company was working on several GameCube projects, including Donkey Kong Racing and Kameo, the latter of which would eventually appear as a launch title for the Xbox 360 in 2005.
However, prior to this Kameo underwent many revisions and was almost released for the original Xbox at one point. YouTube channel ptoponline has been digging through various prototypes and has come across some very early test sequences from when the game was still in development for Nintendo's platform.
The footage is interesting because it shows a monster helper which wasn't included in the final game, as well as some slightly different character designs.
If Nintendo had held onto Rare then Kameo would almost have certainly have been released on the GameCube - would you have liked to have played it on that particular console?