Since there is no official source code available for Super Mario Bros, [Matthew] used a disassembled version to get started looking for the image data.

I think almost every game on the planet that has a sandbox or level creator option has had the first level of Super Mario Bros. on the NES made using their tools and software.

The first level of Super Mario Bros. is a masterclass in game design. And now Shigeru Miyamoto–the genius game designer who gave us some of Nintendo’s most beloved franchises–explains why.