Games just don’t have a long enough tail to make this kind of effort worth it. They aren’t like business software where you try to keep people on the hook for years.

There’s little reason to keep updating a game past its first few post release patches. So you can assume most of their code bases have been untouched for years, were probably written by people who are no longer around, and haven’t been compilable by modern toolchains for a long time.

The tech debt is just insurmountable most of the time.