This is going to be long... Many issues we experience in Civ5 come from a very simple fact that we don't have any real interactions between bordering cities of different civilizations. Sure, there is territory spread, there is religious influence, there are trade routes but all of these mechanism don't even start to mimic real interactions between two cities-territories that exist next to each other. Especially if bordering civilizations are unfriendly towards each other. Let's think of a very common example: city A i located 4 tiles away from city B. They both produce some culture, they have different religions, there is a trade route connecting them. There is some religious pressure between them but it does not really affect anything in everyday life of our virtual citizens. The trade route's yield is calculated basing on traits of both cities but its effects are solely empire-wide. We have some border issues but they are limited to a race for best tiles. When a tile is claimed by one city, the other one can't do anything on its own. We'd need a great general to push enemy borders further from our own. Let's now imagine the same situation n real life. There would be migration between these two cities and since they are very close, migration would be substantial. They have different religions so we can expect some troubles emerging from this fact. Most likely, it wouldn't be the best idea to work farms near enemy garrisons because your beloved wife might change hands or your son could be slaughtered because he didn't believe that the other city's religion is a religion of peace. At the same time, commerce between these two cities would certainly benefit them both and contribute to their growth in a scale determined by wealth of each of them, population, bilateral relations of their owners and level of trust and "similarity" between their citizens. We can imagine that territory and borders would be an ongoing issue. Raids, border clashes, casual raping and other similar leisure activities used to happen all the time thorough centuries, especially when armies were marching. Today, we could imagine additional problems or lack of such: border between a South Korean city and a North Korean one looks slightly different than borders between Polish and German cities (there are none). Furthermore, if city A granted open borders to city B, we would have not only the ability to move troops in their territory (and various problems that arise with armies rolling over land in different eras) but all interactions, positive and negative, would greatly intensify. This list could go on forever. It's obvious that Civ is only a game, a model for whole civilizations where cities are merely a representation of patches of territory. Some elements could be implemented, some would be too complicated and we need to forgo other for the sake of cpu power. Civ5 has enough problems with turn times on higher difficulties. But how should we approach this problem? Answer to this question must be given by someone smarter than myself, namely, the Firaxis team. I can only suggest things that, in my humble opinion, could help evolve numb Civ5 cities into living organisms. First of all, I would enrich all policies and religions with synergistic "neighborhood elements". What do I mean by that? It's quite simple. Let's say that city A is traditionalistic and pious. On one hand, its citizens will most likely be very protective of their land, likely aggressive towards infidels (especially other pious groups) and not very willing to mingle with other people. On the other hand, they would be quite a content bunch, easy to govern and eager to spread their true truths of their only true truth. Let's now imagine that citizens of city B are libertarians who believe in warrior's code. They would most likely seem to citizens of city A as amoral barbarians. At the same time, citizens of city B would see citizens of city A as rather unfriendly and pitifully narrow-minded numbskulls. Such differences would make it difficult for them to trade, develop culture in tandem and coexist peacefully. In game terms, there could be penalties to yield of bordering tiles, "unrest/zeal/anarchy/crime/whatever" city-wide modifiers (penalties/bonuses) and all these modifiers could be further modified by empire-wide relations and later also global policies. This would be a groundbreaking change for Civ franchise because it would mean that society model of your neighbor would actually influence your society. This should be paired with mobile borders. In Civ games, borders are expanded by culture. It's untranslatable to real life. Borders of Greece expanded because Greeks built a nice statue? It's silly but of course it's a game and this mechanism had proven itself over and over again. Nevertheless, its stability bordering with ossification is its huge flaw. It could be changed with a "territory claiming" mechanism. Every city would still have at start a 3-tile potentially available working radius with the first ring unlocked for free, but the city would need to "claim" more land. How? In a very simple manner. Player would either buy the tile he wanted (1 tile per turn, with a citizen still busy for the turn with claiming) or send citizens to claim it by simply working there. Citizen of a city would work for a few turns as a classic worker expanding territory of the city and making yield of the tile available for being collected. This could mean either a) creating an improvement (farm of whatever) making classic workers redundant in game, or b) just expanding territory and making it workable/improvable as in Civ5. Time needed for claiming a piece of land would depend on number of tiles claimed so far and distance from the city core. It could also be modified by terrain type and of course things like policies. Note that there is no culture involved in the process whatsoever. (It's implied but to make it clear: a citizen sent to claim new land would not be able to do anything else until he is recalled or finished. More than one plot could be claimed at the same time, each by a separate citizen, but with penalty to length of the process.) My "neighborhood" mechanism would become relevant in several possible ways here. It could be much easier to claim land near friendly civilizations and societies than unfriendly ones or simply uncharted territories. There could be rivalry for tiles and simply clashes of people undertaken by the game as "special events" of sorts. Hostility between populations of neighboring cities could mean reduction of said populations, reduced efficiency, claimed land returning to its neutral status and so on. Unfriendly societies would actually give real reasons for civilizations to be unfriendly towards each other and friendly societies would make beneficial neighbors. Or at least non-problematic or the-least-problematic ones. Military is an issue that begs to have some more light shed on it. As it was already proposed, military units could protect workers who claim new terrain in places where protection might come handy, or they could oversee borders protecting civilians from any hostilities. In war time, troops could evict enemy citizens from claimed land, reducing this way enemy territory. I must stress here that in history of mankind, land was rarely claimed in treaties. In most cases, your territory was where your home was located and when your house was burned, the land under it ceased to be yours. This tactics is till being used around the globe, e.g. in Israel. A "border pact" could be an advanced diplomatic action that would work as a promise not to move your borders into enemy cities' radii and could be broken as any similar promises (don't spread religion, don't buy land etc.). The most important thing about my "neighborhood" mechanism is that citizens gain autonomy steered by our policies (and possible civilization-specific traits). If we want to be a good neighbor for pagans, we shouldn't go for some of the lovelier piety policies, but if we must have that one fancy bonus to our shrines, we also must accept that our citizens may cause problems both for us and for our neighbors who do not share our dominant religion. This would of course affect all other policies as well, making mercantile civilizations work very well together and cause paternalistic diplomats to be much better neighbors than warriors. I'd also shift influence of trade routes from pure gold and limited science to diverse benefits. All bonuses, luxuries and strategic resources available in city A but not present in city B could not only offer gold but some food and production as well. Those available in both cities shouldn't be simply forgotten either, as it is in Civ 5. Even culture and great people points could be transfered or rather multiplied. I don't want to go into details of such mechanisms because I do not have anything solid to propose on this particular field yet. All the same, trade contacts between cities must mean something more influential than merely some gold and a few (priceless in early eras and on higher difficulty setting in Civ5) beakers. Type and quantity of traded resources could be connected with relations between empires. The whole concept of the "neighborhood" mechanism is aimed at bringing life to completely dull cities. Border tension used to be and still are on of the most important factors in growth of civilizations and still are. Previous Civilization games had various mechanism that were trying to give justice to this element of real life but this aspect haven't even been touched in Civ5. Because of that, civilizations become hostile and friendly toward us pretty much at random. It's happened to me dozens of times that a civilization backstabbed me for no apparent reason and even though they decided to denounce me several turns after our DoF, they did not act upon this denouncement to the end of the game. With "neighborhood" effects there would be actual reasons to start a war, cut down enemy population, move their borders away from our own or just raze the bastards to the ground. I'm not claiming here that I've got answers and solutions that could be easily implemented, yet I believe that this would be a very promising direction for Civilization 6 and would also decrease importance of science, which is the absolutely dominant factor in Civ5. A player would be forced to forgo some of the tastiest policies and religious beliefs in order to survive and profitably coexist in a living world, not only on a dull map. It's also noteworthy that my proposition does not have to eliminate war from the game. On the contrary, this would add logic to warring, provide true justification for conflicts. Don't you have sometimes a feeling in Civ5 that early and mid-game can have conquest just for the conquest sake and late game can turn into a mindless deathmatch?