I agree that there were alternatives to the Eurasian development model(s)/agriculture and they definitely had other species and means for producing food. But I believe there were real limitations to these viable alternatives, which in my mind makes them less competitive (and that's what we're discussing right?). I'm not saying they didn't have agriculture. I'm just saying they didn't have the same intensity in production and rate of development (made possible by draft animals etc). And yes, the European colonisers were very ignorant (and ruthless). Of course I haven't studied pre-colombian history, so I'm basing most of my current analysis on "Guns, Germs and Steel" and various short texts/wiki summaries. From what I've gathered it was the case that Europe had a larger population per area than the indigenous people of the americas (meaning a more effective agriculture), and also more advanced metallurgy and arguably military development. North America never really developed smelting unlike in South America where they did work several metals, e.g. bronze and meteoric iron, but they didn't get to mass producing metal tools and equipment, and they didn't really develop and adopt iron mining and smelting (lack of demand?). Of course, if it hadn't been for the Old world microbes, it would prrobably have been very hard for the European colonisers to invade and settle. On that note it would be interesting to see diseases and pandemics represented in the Civ games, although it would probably just be frustrating to players to lose say 95% of their population. Using the system of demand/need however, one could argue that there sinply wasn't need/demand for more intensive agriculture and metallurgy (apart from prerequisites), which I'm sure you are more knowledgeable of than I am. Vanilla Civ and modern people in general like to view history by the perspective of constant striving to get to where we are today, but the activities and motives of historical peoples are more varied than that. In my opinion the Civ series as wells as many other games/stories have an exaggerated focus on warfare and downplaying of culture. The initial use for metals were for art and jewelry/ornaments amongst other things. Many copper and bronze items were arguably made for cerimonial purposes rather than for war or tools. Game-wise I see 2 major ways to implement these separate development paths: Either you retain vanilla Civs abstract tech tree and development, trying to include all Civs regardless of climates/biogeographic conditions/resources. Where a European Civ can travel to a tropical location with a settler and improve those resources with a generic Farm or Plantation. I guess you could have a lot of Applications/Projects that are dependent on your biogeographic starting point, though I would argue it would be difficult for players to discern which ones that apply to their specific Civ and location. But if we're using a design of unequal/separate development lines, then you could have several different initial lines of development (giving access to similar or slightly different Applications/Projects). All of these lines could join together in the later eras, once the whole world is more or less explored and connected (communications and trade). That should bring the benefit that players would have an easier time overlooking the paths "forward". Although it would also be interesting if possible to remove the visibility of the techs in latter eras, to force players to guess and do some trial and error to find their way "forward".