Hi

Is it possible to make a plugin that will play the old Rust theme in game ?

I don't think so.

Merged post

Music is client-side AFAIK and server cannot just change it.

misticos is right, so it's possible only if client still have this theme somewhere in files which I doubt (can be researched still).

In game:

A. In main menu [not possible]
or
B. In actual game? Like when running on radtown? [possible]