Nightdive did all the porting, and already had a screenshot of a Linux build, they just wanted some confirmation they were building something that was sane and binary compatible, and I'm totally a wizard at that, so I did a build for them to post.
Here's what you need to know about Noctropolis: it was originally an MS-DOS game, written 100% in x86 assembly code.
Here's what you need to know about Nightdive: instead of shipping this in DOSBox or something, they rewrote the assembly to be portable, 64-bit clean C++11. Nightdive is hardcore like you wouldn't _believe_.
Since their rewrite already used SDL2 and SDL_mixer, the Linux port was easy. And while they didn't specifically ask me to do it, I went rogue and did a macOS build too.
All versions are live on Steam right now, and 75% off during the Halloween Sale, so if you grab it now, it'll set you back a whopping two dollars and forty-nine cents.
This game, as a minor butterfly effect, came out of my call for games I could port as part of this Patreon, so while this isn't the biggest game of the year, all of you made this happen.