Mario Kart XXL (Lost Game Boy Advance Tech Demo; 2004)
Mario Kart XXL is a Game Boy Advance tech demo created by Denaris Entertainement Software for Nintendo in 2004. The purpose was to demonstrate the GBA's ability to render and scale/rotate two different background layers. There is only one course, similar to Donut Plains 1, and only one playable character, who is Mario. The race consists of three laps and can be cancelled at any time by pressing X. Unusual for Game Boy Advance games, the course is rendered in true 3D. The camera can zoom in and out on Mario using the L and R buttons, also rendered in full 3D.
The Game Pak is shaped like that of a Game Boy game rather than a standard Game Boy Advance game. YouTuber "Steven Seventyeight" found the cartridge and posted a gameplay video of it using the GameCube's Game Boy Player. He has stated that he doesn't plan on dumping a ROM of the game.