What I find fascinating about this project is it’s longevity. It was started in 1995, a year before Civ II came out. I remember playing it in 2000. And here it is still going. Development is pretty active and there is even a 3D mode.
You allude to the reasons why though, with the box release requirement--though that's a part of the greater economic reasons.
I wish that was the case because then you as the player could be done with paying for the game once. Instead, the current trend is to make games into live services that have continuous development funded with continuous revenue streams. Moch more predictable for the companies to see their revenue slowly go up or down than invest in a completely new game that might be a hit or might flop completely.
There's even a nice talk on SS13 specifically since the project is massive and sees changed ever hour (in a single version, let alone all versions or even the multiple remakes currently in development): https://youtu.be/z5sjwqUten0
EG https://forums.somethingawful.com/showthread.php?threadid=28...
The Readme includes the list of applied patches.
I'm sure someone has probably recreated the campaigns too, though you would be missing the memorable FMV sequences.