Super Mario World 64 is an unlicensed Sega Mega Drive game. It is a loose attempt at porting the SNES game, Super Mario World to Sega's console without seeking endorsement from either Sega or Nintendo.
It's currently unknown who's developed Super Mario World 64, though some believe it was the same group behind Super Donkey Kong 99.
Oddly, for an unlicensed game, Super Mario World 64 features copy protection which makes it impossible to dump the ROM with the most usual techniques, such as using a Retrode. After a few years of unsuccessful attempts it was finally correctly dumped in 2012 and released a year later, though it doesn't work on emulators without emulation of the protection itself, or with a cracked ROM, with the protection removed.