Calapine said:
Well, to start with...Hello! *waves*

I have been lurking here for a few weeks already, but this is the first I time to post. (And starting off with a question right away too...)
Hello and welcome to civfanatics!
Calapine said:
OCN
I am still familar with the concept of 'Optimal City Number' back from Civ 3, but I haven't been able to find the actual numbers. Does anyone know the OCN for small, standard, large, etc.. maps. Also, do game speed or difficulty setting have any influence on that?
Best Regards
OCN is a concept that was invented for Civ 3. If you had built significantly more cities than the OCN, then every further city would be 95% corrupt and thus be virtually useless. Corruption doesn't exist anymore in civ4, thus the OCN doesn't exist anymore (or at least is radically changed in appearance). We now have city upkeep costs which increase with the size of your empire (number of cities, distance of cities, size of cities) and thus limit your rate of expansion by making additional cities very costly at some point. To get a feeling for this new concept, I would advise you to take a look at
the following War Academy article. The graphic can be very enlighning. The reason why upkeep rises that quickly at some point is that as you place more cities, the number of cities upkeep goes up for each and every of your cities (yes also for those that you have built earlier). However, there is a maximum to the number of cities upkeep, so at some point you will reach a plateau. There are formulas in post 89 of the original strategy article (there is a link at the bottom of the War Academy article to the original article). I would only advice you to look at the formulas if you are mathematically inclined.
(By the way, I disagree with the concept of OCN silently introduced in the article. It was written when civ4 was just out and is clearly influenced by the concept in civ3. You should look at each game on itself, this is only confusing people.)
If you want to get an idea how much the last city cost you, then take a look at the income per turn just before and just after settlement of the city.
You can also take a look at the financial advisor (F2) just before and just after settlement and see how the new city influenced city and civic upkeep costs). Remember that the next city will probably cost you more and you have a way to judge if further expansion is prudent at this point. Note that cities that help you control new resources are worth some costs.
At some point in the game the costs of a city are negligible compared to the income of a city (if you build a decent number of cottages). But before income increasing technologies as currency, cost reducing technologies as code of laws and technologies that allow you to grow your cities are available, it might be difficult to make a large empire prosperous. Especially at the higher difficulty levels, expansion can be expensive in the early game.
Next to city upkeep costs, there are civic upkeep costs and unit maintenance costs. However, those usually rise linearly with the size of your empire and should thus not be a severely limiting factor to your expansion. You can read more about those costs in the
War Academy (game mechanics section).