Id Software’s unreleased Super Mario Bros. 3 PC port has been acquired by the National Museum of Play as reported by ArsTechnica.

The port pre-dates id Software’s breakout hits Wolfenstein 3D and Doom which were released later in the ’90s. The Super Mario Bros 3. PC port was worked on in 1990 for MS-DOS PCs in only a week as an attempt to garner a contract from Nintendo to develop an official port of the NES title.

John Carmack even developed a scrolling algorithm specifically for it that was much closer to that of Nintendo’s than the stuttery ’80s DOS-era PC variants. Museum of Play Digital Games Curator Andrew Borman said, “When looking at PC games of the era, there really weren’t titles with the smooth scrolling seen in Nintendo’s hits.”

The ’90s were a big decade for gaming what with the birth of the FPS genre and the start of Valve and PlayStation, but Nintendo had the same mindset it does today: exclusives were exclusive. Its games wouldn’t go beyond its own platforms, so PC was a definite no. That meant that this one-week developed demo with revolutionary sidescrolling for the PC would never blossom into a fully-fledged, official port. Still, the tech wasn’t abandoned.

Id Software “wasn’t deterred by the rejection, [and] the technology was reused for Commander Keen.” For context, that was id Software’s own sidescrolling platformer. It launched in the same year - 1990 - for MS-DOS, again pre-dating Doom and Wolfenstein 3D. It even got its own Game Boy Color port in 2001.

The requisition of this demo is a huge win for video game history preservation as, prior to its find, the closest thing we had to tangible evidence of its existence was a video released by John Romero in 2015 showcasing various demo levels. This week, it was found amidst a large collection of donated software, completely catching Borman off guard.

“The individual who donated it was a game developer,” Borman said, “But they did not work on this pitch, instead receiving [it] during their work. It wasn’t something I expected to see in this donation, but it was extremely exciting, having seen the video Romero shared back in 2015. One of my favorite things at the museum is helping to process incoming donations, especially when we can help share stories from important developers like id Software.”