The GBA saw a number of colors and redesigns throughout its years, but we never saw a Lemon Yellow version. Little did we know that one existed, and there's actually a prototype for it.

Developer Jeff on Twitter shared pictures of this little-known prototype, which was used as a controller for the IS CGB/AGB Emulator kit ver.1. It's a pretty bold color choice, and no doubt one people would have jumped on to purchase. Too bad it never saw commercial release!