I was wondering what lore universes exist where stories and games could take place in.

First ones that came to mind are The Battle of Wesnoth and Pepper & Carrot.

Though can anybody think of any further?

Public domain is also valid, but it has to pd world wide and I’m not sure what that would mean. Authors definitely need to at least dead since 1943, but I don’t know if there were any countries that had more than death+80 (Spain, Colombia and Equatorial Guinea).