It's game-changing so I can understand opposition to it, but I'm curious if there could be a future mechanic where food can be imported from one city to another city, hereby transferring population from high food cities to potentially high production or high commerce cities. Without this mechanic, cities like Memphis end up getting way higher population than Rome in the Classical age. And cities like Minneapolis, Rapid City, Omaha, etc. can get way higher populations than New York or Los Angeles in the modern era. Same goes for small island cities in the Carribean. The game-changing aspect is that it can be used to front-load most of your population in your core (imagine Cuzco with 20+ population).
To keep it from being too game-breaking and to keep it interesting, these are my proposals:
After the discovery of Pottery, you can export land food (any food obtained from a city by farms, pastures, windmills, plantations, grasslands, flood plains, etc.) from one city connected by trade route to another connected by trade route. By default, you can export as much food as you want, but only 1/2 of the food exported from city A will be appended to the total food obtained by city B, which makes it more advantageous to not export food but still gives an alternative to whipping population in the early game. If you run the Agrarianism civic, all food exported from city A can be used by city B.
After the discovery of Combustion, this 1/2 limitation also goes away (represents the creation of barges and trucks to haul food over long distances to limit spoilage, raids, etc.).
After the discovery of Refrigeration, both food generated from both land and sea tiles can be exported (represents refrigeration of fish).
What I like about this idea is that already-existing mechanics in the game can make this quite interesting. If you're Britain or France propping up your core cities with food from your colonies, a Privateer or enemy blockade can easily create disaster if they blockade your cities to break the trade route, thus breaking the food export. It also places a lot less importance on city placement for min-maxing population and allows you to plot cities based on historical, commercial and productive elements instead, which is a lot more realistic.
My only concerns with this idea are (1) how the AI would be able to handle it, if at all, and (2) how to rebalance the game with this mechanic in place. To make it less OP, the penalties and costs for exporting food could also be tweaked.
Any thoughts? Or am I too crazy and idealistic?
