So, there are projects like these;
https://github.com/ihhub/fheroes2
Projects that in one way or another aim to modernize a classic, or try make it more playable on modern machine, or just try to expand on things (like gzdoom does)
what other projects are out there in a similar vein?
I find this a little difficult to search for, even with specific terms (i tried finding myself)
Freespace 2 Open, the games source was released in the early 2000's under a … dubious licence that may or may not be legal to work with but no one really knows and it's been more than 20 years so eh
Freespace 2 far and away my favourite space game, nothing else comes close to the tension of war that game setup so it's great that you don't have to run a .exe from the 90s to play the game. lots of mods for it now too thanks to this project
havent played freespace in so long, ill check those out too