Coming from former RARE employee Lee Musgrave...

“We tried to figure out what to do with it (Donkey Kong Racing. We made a prototype version for Xbox, but because nothing else had been made up until this point, we essentially built it from scratch. For example, if you got knocked off your animal, you had to do a Track and Field-esque button-bashing activity to get back on it.

We decided to try and make it a bit more like Diddy Kong Racing in terms of it being an adventure game. Over the course of the next 18 months or so, it went from being a track-based animal racer to a more open-world game with Tamagotchi-style features, in which nurturing your animal became a key mechanic. It was such a wide game in terms of content, and the development went off into the woods a little bit. It took a long time to do, and at the same time we were trying to build engines for consoles we weren't familiar with.”

This eventually lead to the project fizzling out. Obviously, when it moved over to the Xbox, the game shared the ideas of Donkey Kong Racing, but didn't include Nintendo's character roster.