Actually there was a reason why major European countries haven't claimed core Africa (excluding north Africa) as their colonies till late 19th century - local terrain/climate with compulsory malaria and Tsetse fly (hello, sleeping sickness) + lack of means to travel rivers upstream without steam engines made conquest very hard.
Right now quite frequently by 1770-1780 whole Africa is being conquered by major european colonial nations.
Yes, sure, player or sometimes even AI should be able to perform this feat, it's a game after all. But I think that there should be some kind of mechanic (and I don't think that it's really hard to implement) that should at least make conquest a little bit harder. Even maybe something like increase of coring cost...
P.S. But please, please, please do not boost their tech level!
Right now quite frequently by 1770-1780 whole Africa is being conquered by major european colonial nations.
Yes, sure, player or sometimes even AI should be able to perform this feat, it's a game after all. But I think that there should be some kind of mechanic (and I don't think that it's really hard to implement) that should at least make conquest a little bit harder. Even maybe something like increase of coring cost...
P.S. But please, please, please do not boost their tech level!