Probably some old PC game for use on Windows 98 from a thrift store or somesuch.
I don't buy new physical PC games. I want to, but they're just glorified keys for Steam or Origin unlocks these days - the day the relevant DL service goes down, those discs are worthless. I've heard places like IndieBox are trying to eschew that, though; should look into them one of these days, I guess.