The core of the problem is that each tile is handled the same regardless of what it produces, so a single 'farm' tile requires the same population to work as a single 'town' or 'mine' will. So you'll never end up with a case of low population density farmlands like the midwest USA because those cities will need to be just as large as your production/research centers in order to be able to work all of the tiles needed to produce enough surplus food. If Civ abstracted population more it would be easy, but then it wouldn't be Civ anymore.
There's another approach that wouldn't require abstracting population: introduce an economies of scale mechanic with diminishing returns similar to the one that was used in MULE (
http://en.wikipedia.org/wiki/M.U.L.E.) where adjacent properties (tiles) engaged in the same activity get a production bonus and have the bonus apply at a diminishing rate. Here's how I propose it could work:
- A tile is an agricultural tile once a farm has been built on it or a food resource has been improved;
- Adjacent agricultural tiles that are being simultaneously worked by the city get a food production bonus (economy of scale);
- An agricultural tile with one adjacent agricultural tile would get a food production bonus of X;
- An agricultural tile with three adjacent agricultural tiles would get a food production bonus of 2X (diminishing return to scale: you need two more adjacent farms to get the extra X);
- An agricultural tile with six adjacent agricultural tiles would get a food production bonus of 3X (diminishing returns to scale: you need three more adjacent farms to get the extra X).
The step progression in the threshold for higher bonuses fits neatly with the new hex pattern for the landscape. It would hopefully be relatively easy to mod, since you wouldn't need to change any fundamental game dynamics (well, I guess it might become necessary to rebalance growth thresholds somewhat). Farms in the outer ring would be unable to get a higher bonus than 2X - arguably you could put this down to spoilage during transport or something...
Assuming that a city were to completely specialize in agriculture, the total food production bonus would be: 6 x 3X + 12 x 3X + 24 x 2X = 102X. Based on currently available data (thanks Arioch for an excellent website), a city working 36 grassland tiles improved with farms would produce a minimum of 108 food (subject to modifiers like adjacent to river, civil service, other?). So, in effect, if X = 1 unit of food, an agricultural city could effectively double its output and serve as the "breadbasket" of your civilization.
In terms of food trading - why not base it on the existing trade route system in the sense that it would need to be run through the capital? Here are my thoughts in this regard:
- The capital collects a portion of the food surplus generated by (agricultural) cities;
- The collected food is then distributed first to cities with food production deficits and then equally among (non-agricultural) cities.
The portion collected by the capital would be determined by the player. The terms in (parentheses) indicate variables that would need to be determined by the player. That is, you would need to indicate whether a city was agricultural or not. Conversely, those terms could just be dropped and the mechanic simply be applied to all cities.
The distribution could be equal in a simple sense (i.e. same amount of food sent to each recipient). This would have the effect of increasing the growth rate of smaller cities relative to larger ones (assuming old growth threshold mechanic). Or it could be equal in the sense of distributing the surplus pro-rated by city size.
I would argue that this is a relatively simple mechanic, free from the micro-management concerns that some people have voiced, but I'm always open to constructive criticism. (My thanks to Aussie Lurker for turning me onto the trade routes idea).
I really like the idea of empire-wide agriculture (I started a thread about it earlier). In my opinion, it has the potential to make each city in your empire matter much more. Consider: under current game rules, if you lose your "agricultural" city, what's the upshot for the rest of your empire? There are empire-wide effects in terms of lost science and culture production, but there's pretty well zero impact on your other cities. Now, consider losing your agricultural city if its food were to be supporting several other "industrial" centres. Suddenly, they're starving. Population drops, happiness may be impacted (I seem to remember that starvation was a factor in happiness in previous games), and production begins to grind to a halt. It raises real strategic questions with respect to how you want to build your empire. Do you make each city self-sufficient, but sacrifice the productive benefits of specialization? Or do you build a web interdependent cities that are able to specialize and therefore attain higher levels of production? When you're about to invade, do you go for your opponent's centres of production or their food supply?
Regards,
Pooh