I'm a compulsive builder and a compulsive terrain developer. The game just doesn't seem done until every tile on the board is fully developed and fully utilized. Isn't that the goal of civilization, maximum utilization of the planets resources? Of course this means I've never completed a game because by the end each turn takes 4 hours to complete.
I want to play a cross between SimCity and Civilization. In SimCity the complexity comes from the second-order effects of building something. You zone a region for industrial purposes and it pollutes your water supply, you allow gambling and crime goes up, but your relationships with neighbors are non-existent or always trivial and positive. Your neighbor needs X so you provide it and everyone benefits.
In Civilization building is always positive. Build a factory more production, build a university more science. You never have a case where building X damages Y, so there is no need to balance choices, just build build build. The complexity in Civ is trying to determine the build order. If you choose to build too early your neighbor attacks your city and destroys something of value, if you build too late your neighbor completes the wonder before you do.
I want a game that has the complexity of both, I need to have a reason to NOT build something rather than a continually updating priority list of when to build something. Since I don't have that in CIV I'm always fighting the desire to build everything and stay at peace as long as possible, and find myself fighting little fires on my way towards perfection. For SimCity I need a reason to place the factory in a less than ideal spot, rather than let the clock run at 100x in order to place it in the best spot.
In the end both games end up in the same final state. Perfection in the year 10000AD. The only difference is the path taken to that. In SimCity it is methodical tile by tile and never an incorrect move, in Civ it is haphazard with numerous things that must be undone or taken out of order.
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Some more extensive thoughts on what this might be like:
I actually think the whole game would be a lot better if cities were removed. Replace cities with improvements placed directly on the tiles, but have those improvements be automatically upgraded according to some budget directives.
I imagine a game where each tile has a number of values associated with it including:
Production quantities: food, science, commerce, industry
Influence values: race/language, religion, military strength
Instead of building cities you would place objects that have a regional effect. You would start out with a camp (level 1) which gives you military influence over a small area from which you collect from the four production quantities based on that influence. You then get to budget from the collected production how much to dedicate to building up existing improvements or building some other improvement.
The kinds of improvements would be either improvements that increase production levels: farms for food, school for science, etc... or that increase influence values: roads for race/language, churchs for religion, military bases/camps for military strength.
The production improvements would be dependent on other accessible production improvements. In order to level up your town X+1, you need to upgrade the roads and nearby farms to provide sufficient access to food. Similarly to level-up a factory you need a town. You could set global budgets which would cause existing improvements to level-up to the point where they either outstrip nearby resources or
the budget balances the increased upkeep requirements of the higher level. Similarly if you under-budget then your farms and towns can level-down. You would be be able to override the global budget in particular areas to make a region have a particular purpose (a farming area has a low industry/commerce budget but a high food/transport budget).
Each of the influence types would be better at extracting one kind of resource over another. For instance high military strength allows a lot of industry and food extraction, but is not very good at science and terrible at commerce. Roads complement military strength by being good at science and commerce but not doing much for food or industrial extraction (althought they increase the range that all production quantities can be transported). And religion negatively affects science, but is great for food and commerce and spreads faster.
The rate of growth of each influence type would be dependent upon the others. So if Civ A has high religion, but low military and transportation and is trying to spread into Civ B which has low religion but high military and transportation then the more fervent religion of culture B would be slower to grow into those tiles that are more strongly "A's"
The whole notion of the borders of a civilization would be more fluid. A tile can be simultaneously A's because A has a strong military presence, but also B's because of the religious affiliation of the citizens, while C keeps an interest because the people in that tile used to be C's until they were converted to another religion and held under the military rule of a third. As a result all get some share of the output of the tiles, and all have ways to increase their control. C for instance my build a nearby military base to try and increase his military influence (a cold war) or directly attack the military base of A (a real war).
You could even have civil wars if you let your civilization get too out of sync with itself. Areas that are under-funded and have their own race or religious affiliation distinct from that of the surrounding tiles may revolt and align themselves with a spontaneous military uprising that requires your attention to put down.
It would be like a competitive SimCity where placing a police station is not just an effort at eliminating crime in my city, but also trying to steal the benefits of my neighboring cities.