Supply chains! Logistics! Believe me, you do NOT want that micro-management nightmare! Years ago I played IIRC Sid Meiers Colonization, which was to colonize the Americas from Europe. It had several different resource raw goods types, several different finished goods types, population was specialized to work in different facilities, there were lots of facilities, and to move it all there were several standard ship designs. I gave up my first game after I declared the Revolution in 1776 for Historical reasons. Reaching that point took 4 months (over 1500 hours gameplay). I had the maximum of IIRC 40 cities, about 90 ships, about 30 working population and 20 military per city, and a turn took between 10-15 hours to setup. I gave up because the miserly King of England only sent a few of his military per turn to attack and I calculated that it would take him another two months of play time to end the war. But I scored a moral victory IMHO.