Super Mario World receives the widescreen emulation mod it deserves - The Verge

But for anyone else, a new widescreen hack for Super Mario World means you can now enjoy the 1990 game on modern displays, without having to put up with black bars or a weirdly stretched image.

Super Mario World Widescreen is the work of ROM hacker Vitor Vilela, and works by modifying the original game’s ROM when played through the bsnes_hd emulator.

Although this hack just covers Super Mario World, the hope is to develop a standard that can eventually be applied across all SNES games