Random fun, or perhaps just signs that I'm getting both old and weird.
In finding myself in the mood for some Advent, the only version I've ever encountered on modern platforms is the version from OpenBSD's games install set. Which shows some of the joys of FORTRAN to C conversion. The code looks like the most significant changes it's seen in years are just related to security measures ala OpenBSD. Since I don't have a machine running that OS handy, it's not a quick login and run.
In debating how much poking and prodding getting code to compile on one of my Linux or Windows environments, I came across a fun little fact. ESR has a repo on GitLab dubbed Open Adventure that both compiles on Linux, and has tried to make the code more legible to modern sanities.
While trying to figure out the game from its source may be a surprisingly good idea, l find it rather covenant that it compiles and runs. Because while poking around code is what lead me to the mood to play advent, that's a bit of a different activity from porting advent, lol.