Islands have randomized or fixed "fertilities." One island might be able to grow hemp and cider, while another is required for wheat and herbs. This forces geographic expansion and aggressive logistics management, as no single island can produce everything.
You cannot achieve a high-level Occident metropolis without resources from the Orient (such as spices and quartz), and your Oriental settlements rely on the Occident for materials like glass and iron. This necessitates a massive, finely-tuned network of automated shipping trade routes. ⚙️ Economy and Production Chains Anno 1404
Anno 1404 is widely considered the peak of the "classic" Anno formula before the series experimented with futuristic settings ( Anno 2070 and Anno 2205 ) and before the massive scope of Anno 1800 . Islands have randomized or fixed "fertilities