The Commodore 64 finally has an almost-perfect port of Super Mario Bros... aaaaand it's gone. A developer calling themselves "ZeroPaige" spent 7 years making an impressive port of Nintendo's classic NES action game, but it lasted about two days in the wild before Nintendo let slip the lawyers of war and issued takedown notices.
The Commodore 64 found its way into many homes worldwide throughout the '80s thanks to its versatility and affordability. Though the computer's been long since discontinued, it still nurtures a big programming and homebrew scene (speaking personally, my brother ran a Commodore 64 BBS through the late '90s). The Commodore 64 has its own library of impressive games, but the ancient tech was never meant to run NES ports. It's especially hard to program a smooth side-scroller, which makes ZeroPaige's work that much more impressive. There's slowdown (especially when Mario grabs a Starman), but none of the screen hitching that's common in side scrollers written for retro computers.
It's not the least bit surprising to hear Nintendo pulled the hangman's lever on this Super Mario Bros. port. The company's infamous for going after ports, ROMs, and even stand-alone fangames that take years of development. The excellent Another Metroid 2 Remake (AM2R) took two breaths before Nintendo slashed it off the Internet. Nintendo's even harder on ROM sites, some of which have been sued for millions.
It's a shame, because the Super Mario Bros. Commodore 64 port exists as a technical showcase more than anything. Anyone who wants to play the first Super Mario game will undoubtedly do so through the Virtual Console or a Nintendo Switch Online download, not through a link distributed on Commodore 64 message boards. Seems like an illicit port is an illicit port in Nintendo's eyes. It might be a game company, but The Big N doesn't play.