I was wondering if it would be a good idea to increase the production cost of settlers, possibly through some sort of scaling. In my experience, the initial settler is costed just about right (i.e. it's a significant investment), the second one comes out more easily, and after that point production cost is no longer a limiting factor for getting new cities - I'm more concerned about suitable locations, happiness, and my ability to defend the new settlements. Personally, I would like each new settler to take a while to produce, no matter what stage of the game we are in. Possible scaling factors to increase the cost of settlers could be number of cities, happiness and era. If it wasn't too hard to implement, counting active settlers as additional cities could be a way to prevent players from gaming the system. Ideally, costs would scale so that, by the time you get colonists/pioneers, the cost of a regular settler is the same as a current upgraded settler - that way, colonists and pioneers could be a strict upgrade without increasing unit cost. What do you think?