I've seen a lot of ideas for the aquisition of unguarded, neutral resources outside of your territory. I have one idea, myself, that I think would allow this without breaking the balance of the small-vs-large empire rules of Civ V. This could probably be made with a mod in the future.
The idea is to give the option to make settlements in addition to cities. A settlement would function like a minor city or an "expeditionary" force, built specifically for the purpose of accessing a valuable chunk of land. There would be several pros and cons to this:
Pros:
Would not effect (or much lesser effect) on cultural requirements for social policies
Would, obviously, give territory access to valuable resources
Much less unhappiness from the settlement itself, if any, and limited population growth would keep down population unhappiness
Could make a trade route to offset costs
Could be converted to a city at any time
Cons:
Costs GPT to maintain, much like a building in a city
No culture production
No science production
No great people production
Territory can only be expanded via gold and has an increased cost
Limited tile working bonuses for production, gold, and food
Max population limited
Greatly reduced options for buildings and units
-Could only build workers, settlers, scouts, work boats
-No wonders
-Could only build simple production-based buildings, granaries, seaports, harbors, lighthouses, etc.
Extremely poor defense, easily destroyed in war, and good gold bonus to conquerer (to discourage settling in hostile areas)
Side notes:
Settlements could easily be named and identified by placing "New" in front of the traditional city list name (New Berlin, New London, New York, etc).
For ease of modding, settlements could be identified by a new "base camp" building, similar to a palace in that it would be built instantly with the settlement. This building would have no benifits and would contain the maintenance cost of the settlement.
Commerce and liberty social policies could have advantages on settlements
The idea here would be to make a costly option in a desperate situation. For example, if you direly need iron, but making an entirely new city would cripple your empire in the future. Or, a rich but unhappy civ needs an extra luxury not easily available by trade or city-state alliances. This could also simulate interesting historically-similar events, like England settling America and needing to defend its infant settlements from native forces.
Due to costs and limitations, puting settlements everywhere would be foolish and trade options would still be an ideal first step. However, in times of cautious expansion or desperate need for vital resources, this could be a viable, realistic, and balanced solution.
The idea is to give the option to make settlements in addition to cities. A settlement would function like a minor city or an "expeditionary" force, built specifically for the purpose of accessing a valuable chunk of land. There would be several pros and cons to this:
Pros:
Would not effect (or much lesser effect) on cultural requirements for social policies
Would, obviously, give territory access to valuable resources
Much less unhappiness from the settlement itself, if any, and limited population growth would keep down population unhappiness
Could make a trade route to offset costs
Could be converted to a city at any time
Cons:
Costs GPT to maintain, much like a building in a city
No culture production
No science production
No great people production
Territory can only be expanded via gold and has an increased cost
Limited tile working bonuses for production, gold, and food
Max population limited
Greatly reduced options for buildings and units
-Could only build workers, settlers, scouts, work boats
-No wonders
-Could only build simple production-based buildings, granaries, seaports, harbors, lighthouses, etc.
Extremely poor defense, easily destroyed in war, and good gold bonus to conquerer (to discourage settling in hostile areas)
Side notes:
Settlements could easily be named and identified by placing "New" in front of the traditional city list name (New Berlin, New London, New York, etc).
For ease of modding, settlements could be identified by a new "base camp" building, similar to a palace in that it would be built instantly with the settlement. This building would have no benifits and would contain the maintenance cost of the settlement.
Commerce and liberty social policies could have advantages on settlements
The idea here would be to make a costly option in a desperate situation. For example, if you direly need iron, but making an entirely new city would cripple your empire in the future. Or, a rich but unhappy civ needs an extra luxury not easily available by trade or city-state alliances. This could also simulate interesting historically-similar events, like England settling America and needing to defend its infant settlements from native forces.
Due to costs and limitations, puting settlements everywhere would be foolish and trade options would still be an ideal first step. However, in times of cautious expansion or desperate need for vital resources, this could be a viable, realistic, and balanced solution.