Carnivalé

Based on the obscure animated movie of the same name, Carnivalé has you start off playing as a cat, tasked to rescue your friends by winning Micro Machines-style races. While both this and a Nintendo 64 version were scrapped, most likely due to the movie not seeing a North American release, a ROM of the GBC version was found in a lot check archive that was leaked in September 2020, indicating that at least it was nearly (if not fully) completed.