Related but not totally on topic:

How much would it cost to buy the rights to an essentially now semi-zombie game, that may have been been popular a decade+ ago?

Say a wealthy benefactor wanted to do so strictly to open source and preserve a series, not create new titles.

Maybe for a series that stills sells copies here and there, but is well past it’s prime?

Say, the Empire Earth franchise?

Or something with relatively more recent releases, like Heroes of Might and Magic?

Would it be the millions? Would one be able to do so for individual titles within a series?