So we all hated the city spamming that took place in Civilization.  The problem with Civ was two-fold.  Food resources were generally evenly distributed across the landscape, meaning you had cities everywhere.  To make matters worse, food could never move so cities always popped up around food resources.  Not only that, but by late game virtually any landscape, almost deserts even, could support a worthwhile city.  With my solution, there simply isn't enough food existing on the map to make even 25 percent of the world colonizeable, even with tech upgrades and spell bonuses.

Stopping city spam should be easy.  The devs only have to do 2 things, which I'm surprised not many people have mentioned yet:

A: Make food limited and localized to specific types of landscapes.

B: Make food fluid and moveable.

Basically, food would be limited to certain fertile pockets or crescents along rivers (and players would generally start near these regions).  So let me illustrate (don't get hung up on the numbers, this is just hypothetical.)  The vast majority of regions on the map would have a diversity of resources, but not have any "fertile ground" that can accomodate food production so food from fertile regions would be shipped in.  So let's say you control the Teullon Valley with it's 5,000 available food resources, with each food resource accomodating 1 citizen.  There are 4 regions surrounding the Teullon Valley, only 1 of which has a food resources (1000 available).  If you wanted to spam all 5 regions wall to wall with cities, you'd need 100,000 food resources.  First, you naturally colonize the fertile region.  From there, you are left with a variety of decisions.  Do I colonize the Orgonian Mountains to exploit their rich metals?  Do I plunge into the Moonglow Glade to exploit its exotic animals and wood?  Do I colonize the Wind Swept Coast to pick up those extra 1000 fish food resources, even though I have to spend a hefty amount of research to do so (and the not to mention the magical fire coral there aren't as valuable to me as the metas of the mountains.)

You would have a little icon somewhere on the interface (probably near your treasury) that would display how much free food was available.  Every time population grew anywhere in your empire, your food would decline.  Every time you built a new farm or fishery or what have you, it would increase.  Population wouldn't grow if you didn't have enough food.  This seems like the most intuitive, simple, and realistic way to stop city spamming.  Once you've "capped out" on your food, you'll have some even more interesting decisions. 

Do you improve your food research to exploit new types of food resources or improve existing ones?  The food you have so far has only allowed you to colonize 10 percent of your 5 region area, so improving food research will allow you more dense colonization.  

Do you move onward and conquer neighboring cities of opponents?  Even though your home territory isn't exploited to its fullest, you could always just grab low hanging food resources from your opponents.

Do you simply improve upon the non-food resources that you already have and ignore food growth alltogether?  It may be that quality rather than quantity is the solution.  You could always just grab the most important pockets of resources in all 5 regions and arm your soldiers very, very well.

Add essence to the mix in order to build a city and you end up with some interesting choices.

Naturally, you'd need a few tweeks so that people don't spam a billion, 1 citizen cities all across the landscape, but overall I think the idea is pretty solid (so please refrain from stating a simply resolved problem).  Also, there are some other, very interesting ideas that spin off of this one, but I'll await some feedback.