Eiyuu Senki and Gold (borrows historical figures and fictional characters from our world like Columbus. Magellan, Ivan the Terrible, Da Vinci etc.) {Hot take incoming: I like Gold more than the original because it has so much more girls and it gave h-scenes to girls that didn't have one while reducing h-scenes from characters who has a lot and that is what I like. If you have so many roster of girls, you gotta make them have h-scenes at the very least and not just focus on a handful of them and ignore others}
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(planets instead of countries but they do resemble countries from ours, you even got idol not-hitler here) [Japanese only, there is an MTL but wouldn't recommend it]
Daibanchou (more localized area in japan instead of different countries it's more of different cities)
+1 Eiyuu Senki World Conquest
I much recommend the fantranslation over the official English publication.
and if Renryuu counts, then maybe Princess & Conquest, too.
but I can not recommend it, as I played it long time ago (had some fun with it), but heard it has inbetween become increasingly unstable?
(much too heavy for that limited old rpgm engine)