I am aware of multiple threads on this topic, but I havnt seen anyone having quite the same take on the problem as I have. So here goes:
The reason city spamming is a good strategy is that more cities gives more production, control over more resources, more land and so on. This is standard 4X functionality.
I think that PEOPLE should be the limiting factor to avoid city spamming. The population growth in a city should be based on more than a standard percentage or the influx of food (CIV IV). Population growth is based on birth and immigration (could be limited by emmigration).I assume here that the number of people in a city is strongly influencing production capasity in said city.
I also assume that people attract people. That is that immigration is based on the status of the city, but also the size. The size factor could be a percentage (based on race and other modefiers). A city of 10000 people would attract 200 people a year (2%) and a city of 100 would attract 2 (2%) people a year if the status is the same of both cities (normally the large one will attract a higher percentage due to the higher status of the city).
1. As far as I understand there will be no settler unit, but the settlements are created by our main channeler. I would say that it would be a good idea to have all new settlements get their first inhabitants from the cities that the player already owns. This will slow spamming considerably.
2. If people are immigrating based on a city`s status then the cost of city spamming will increase. The extra city will cost money to sustain, but it will grow very slowly due to its low status until it gets the right buildings and more people.
The 100 people used for a settlement would grow at (just an example here) 2% a year if they are in a large city, but only 0.5% if they are in a small settlement. The cityspam tactic will then lower growth for quite a while.
3. Since production time of new buildings and such will be very long in new settlements, a tactic of city spamming will grind your growth to a halt as you dont have enough people to get your cities thriving.
The result of this is that the player will have to balance growth of the major cities with the construction of new settlements. Expanding from 1 to 4 cities in a short time will stop the empire growth for a long time, while a more controlled growth with one or two smaller cities at a time will give better results short term and long term. Ofcourse any race with extra growth bonuses (high birthrate, high status giving more immigration) will have more potential for a bit of spamming.
Is this understandable??