The subreddit has a small community of people playing. iirc there's a community server you can point the Gog.com binary to: http://old.reddit.com/r/nox. (The Gog.com binary actually runs on macOS if you're pre-Catalina as it's 32bit, they just removed the indication since everyone is on Catalina now)

The browser "port" is here: https://playnox.xyz/ (200mb) -- Whether online play is available or not can be hit or miss. The single player campaign does work as well -- worth it for insta-nostalgia.

I say "port" in quotes because it's not just a matter of `cat nox.exe | emscripten > nox.js` of course. The creator posts in the subreddit / the nox community forums and has some really interesting technical comments where he explains some of the challenges.

People who can pull off something like this (talk about cross-cutting engineering skills) really blow me away.