Kirby Air Ride beta version (lost video game build; 1996)
Kirby Air Ride is a Nintendo GameCube game that was released in 2003. It is a spin-off in the Kirby franchise and, as of 2016, is the only racer game in the series.
The game had a very lengthy production spanning from 1996 to 2003. At E3 1996, footage from the game (then called Kirby's Air Ride) in a very early and different state was shown. Not only was it on a completely different system (the Nintendo 64), but it appeared to have started out as an adventure-racing game, a type of game that was rarely if ever made back then. Not much is known about how different it would have been to the final product, but several videos have found their way onto the internet, which show additional early beta footage (mostly in the form of pre-release advertisements).
There have also been some unconfirmed claims that what eventually became City Trial was originally supposed to be bigger and more ambitious. Very little early footage has been seen of City Trial, but in the final release, it's rumored that the player can exit City Trial's boundaries and see distant islands. These would either simply be background objects or may possibly be remnants of the expanded City Trial.
Besides the aforementioned videos, little other early material of the game has surfaced.