I think colonization TW would be great, it could begin around 1492 and end in the 18th century, there would be Europe, America and Africa on the map (perhaps Asia too) and you could play as one of the european powers trying to bring christianity to the natives and gold to their homelands while fighting the natives and the other europeans, or you could play native peoples trying to save their lifes and their culture/religion, addon could be for example african pre-colonization kingdoms or mayas/aztecs/incas or something like that.
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