"like Rome approaching a million people"
- You mean about a population of 15, right?
I'm not sure what the Civ-equivalent is, but it surely isn't the size 12 limit (after aqueduct pre-sewer) it was in the old Civ games. That scale isn't worth jack anyways...the Roman Empire, at its height around 100-180 AD, had 100 million in population, and Europe's total population was around 120 million. The modern world population is roughly 6 billion. Try building that in Civ.
So, if we just ignore the scale and think about it this way: ancient empires could build massive cities just like modern ones. People look at the ancients and say: "They are technologically backwards, so they must be socially backwards as well." It's a false assumption.
I would think that the way to represent that would be the existence of a Small/National Wonder allowing growth of the city it's in past certain of the hard limits; or possibly making that a property of one's capital.
Why add all this extra stuff (I'll censor my language) when the current system can represent it just fine? Look, your cities still don't get huge in the ancient age unless it is very well-placed and has good access to food. In the modern ages, you get new buildings to increase the limit like hospitals. What I don't understand is the arbitrary limit: why 6? Why not 8? And if it's 8 why not 9?
I am not fond of most methods proposed for plagues because of the randomness; at least if they are to be implemented, make them depend to an extent on things one can control (be more likely with overcrowding of insufficiently developed cities, allow one to have improvements that mitigate the effects, and so on.)
That's what health-boosting buildings like aqueducts, grocers, and hospitals are for, to name a few. A single population point lost to disease is not much. And, if you build a hospital, then you aren't susceptible to that event any more. Thus, there is some player controlability over it.
However, this is a completely unnecessary add-on, because the core "penalty" for exceeding your current health cap is 1 food per citizen. It's simple, and you can control it through trading resources, field improvements, and city buildings.
Which compared with a couple of hundred cities on one of the larger-sized Civ 2 or Civ3 maps still feels small to me.
There is a giga-map mod that makes the maps larger for Civ4, so you can have 100's of cities! That's right, you don't have to post and wait, it's already here! Sounds like you are the target audience!
This is one where I think the Rise and Rule mod hit the best answer I have yet seen; in addition to buildings reducing corruption as the game goes on, have a number of National Wonders become available over the course of the game which serve as a second, third, or fourth centre for corruption calculations, effectively regional capitals. That said, cities with severe corruption and waste are of more use than they look, one just develops them for maximum food generation capacity and turns them into specialist farms, as specialist science/tax input is not affected by corruption.
So it just cheapens the use of additional centers of government? Civ4 handles this in two ways: you have your civics maintenance and your city maintenance. Both penalize your empire financially if you get too big and are running it inefficiently. Tell me, do you think it makes much sense to make specialists immune to corruption but field labor is heavily punished?
I am unconvinced on this; it seems unduly coarse-grained, and I prefer finer control.
It encourages players to develop specialized cities, and gives a boost to those empires that have established infrastructures over the flash-in-the-pan REX style empires. Plus, there is the courthouse improvement, which cuts maintenance, and the Forbidden Palace (still has the same effects as Civ3). It's a good blend.
Just like cutting out the city-based unit maintenance and replacing it with the national unit maintenance. City-based maintenance of a shield per unit was just tedious and annoying. With national maintenance, you still have to pay to upkeep a large army but it eliminates the tedious and annoying micro. And yes, I know you want more complexity and micro. But this is not the good kind of micromanagement, this is just the annoying book-keeping kind.