As many people have pointed out the current food & housing system is a bit odd and not well liked. The reason I think is because you use food to build houses which doesn't make sense as those houses could be empty. And once the houses are built you can proceed to lose your food production and while it will become negative there is no real penalty. Also once a city has reach the desired level there is no incentive to maintain the current population. You can simply demolish the houses in favor of putting up production facilities. The same goes for the Prestige buildings as once you have reached the max amount of people needed the buildings become useless and ripe for demolish in favor of better buildings.
That being said what I propose is a real shift on how these things are looked at and used in the game. The objective of these changes is to makes sure they make sense from a strategic point of view and that they stay important throughout all stages of the game. Also since this is more concept then hard numbers I'll try to stay clear of using actual figures as that falls under balancing which can be worked out later. Anyway down to business.
Obviously food should be used to feed the people. So the question is how to go about doing this. Well since the economy is global with all resources treated to one giant pool it stands to reason that food should be the same way. Though it's not just resources but also population that shows up on your global resources.
This provides a bit of a unique opertunity as we can use the global population to determine the food consumption as it also includes your army units. Thus if you build a large army it could end up eating most of your food. This way late game players won't be able to simply withdraw large numbers of their population into their army as a way of avoiding having to feed them.
It seems obvious that while food is in surplus the population should grow. The real question is what happens when there is a food shortage. Well a couple things can happen, first the most obvious is some of your people die from starvation and second your military units become less effective either from some penalty of maybe some HP loss. The exact amounts and figures to be determined during a balancing phase.
The question on how to manage a shortage can be handled several different ways.
1) The player has not control over which villages starve.
2) The player can assign priority on a sort of resource priority page which simply list the order in which towns should be given resources in case of shortages.
3) Similar to 2 only the player could choose to spread the shortage evenly thus no one city takes a major hit. Including possibly a mix with a High/Med/Low priority setup.
4) If a military penalty aspect is in play for food shortage then the player can choose which gets priority the military or the civilians. This would work best if the military actually takes an HP hit and can't heal until food comes in surplus again. After all if the player is damaging his resource gather base by starving out then the other option should also be damaging beyond simply a weaker atk/def for a single round. As in both cases the losses can be naturally recovered once food supplies are restored.
This also allows for the option of sieges that cut off food supply since as the mechanics for a starving population will already be in place.
Prestige I think is ment to represent how popular and atractive a city is to potential citizens. While right now it serves as little more then a counter for how many people move in each turn. I think a much better approach would be to use prestige as a more dynamic tool that is sort of another cap to population as well as housing.
What I mean by this is the higher the prestige the more people move in just like now but at the same time the more people that are in your city the slower it grows. After all as the city fills up it becomes more crowded and less atractive to new citizens. Unless you continue to improve it with things that will draw people's attention like inns, pubs, theaters, and town halls.
So it becomes a bit of an uphill battle as the more population you get the slower the city grows which means you need more prestige to help make it grow faster. And of course there will be some point at which having too low of a prestige will mean that people actually start moving out of your city. This means that you will need to maintain a decent amount of prestige to keep your citizens happy and staying in your city. It will also make many of the currently useless prestige buildings serve a purpose.
Obviously given the change to food the houses shouldn't require them anymore. But given the changes to Prestige I think most of the housing buildings should give some prestige. Though I also think huts, housing, and Villas shouldn't be auto upgrade. As the higher ones should give more prestige and cost more as well as giving more population cap like they do now. The option to upgrade without having to demolish the old building and building a new one should be implemented as this would be a good feature in general since many modders will likely want to have building upgrades that are not automatic.
This new setup could make houses with high prestige such as estates more worth the investment. Along with even more potential to make the slums matter as a choice. Several people have already noted the slums need either more population support or less food usage. Under this setup though the food isn't really an issue though it probably would need a larger population cap. But overall it does open up some possibilities which would need to be worked out in balancing issues but the basic concept is there. As it's a trade off with faster population growth of high prestige but lower housing cap vs a higher housing capacity with slower growth. So it'll be kinda like it is now except growth slows down as the city gets closer to being full and you need to maintain a curtain amount of prestige to keep your citizens.
Final thoughts and other ideas
This setup makes it so in a way you have 3 things determining your population capacity but each one has a different effect so it's a bit of a balancing game. As food not only applies to your citizens but also your military there is the need for large amounts of food. While prestige has more of a morale effect on cities by not only effecting how fast they grow but also how much over crowding they will tolerate. And lastly the housing is of course the population cap for the city but also allows more types of bonuses to be applied to different housing effects in not only prestige but also possible other things like gold for "taxes".
While the proposed system includes some changes to all 3 areas they are not really dependent on one another. Like the food change could be made but the prestige could remain the same or have a completely different approach. And like I said before this is mainly an exercise in concept rather then specific numbers and balance. So things like how much food a farm should produce of how many people 1 food should support and all that stuff can be addressed at a later date. Even the figures currently in use on food, housing, and prestige haven't gone through any balancing so don't rely on them as a basis of comparison when it comes to numbers but rather compare how their mechanics work.
Before I wrap it up I'd like to close by covering another problem that exist under the current system, which is population only matters for leveling up the city. Once a city has reached level 5 there is no real reason to keep the population around. The city will not de-level even if you demolish all of the housing/prestige buildings. This quite frankly is not a good thing as you should want a player to need to keep that level 5's city at or above 1000 people to really get it's benefit.
I think the easiest method to make players want to keep the city's population up after reaching that level is by having a modifier of something like (Current Population/Required Population for Level) apply to the output of buildings in the city, it would max out at 1 so you'd need to put a cap on it since it's only meant as a penalty if they go under. Thus a level 4 city which requires 500 people to reach with only 400 people in it would only produce at 80% efficiency. This combined with level multiplier I've read about mention would really make a huge difference.
I only recently read about the multiplier and didn't really notice it in the beta so not sure if it's in, was planned but then scraped as some post in forums are old so this next part could be off. But supposedly a level 4 city has it's buildings produce at 4 times the amount thus a market with 1 gold is actually producing 4 gold. Well under the suggested modifier above a level 3 city with a base produce of 10 would produce 30 goods. While a level 4 city would produce 40 but because the level 4 has a higher multiplier it could drop to 75% of the needed 500 population before it's production was less then that of the level 3 city.
Of course that is a very basic setup which is easy for the player to understand. A much more complicated one with the population production penalty more closely matching the curve from level 3 to level 4 population vs bonus given could be down but then you'd probably also need to take into account the increased number in building slots and such. But that seems like more of a headache. Especially when the goal is quite simply have the player keep their population above the level required by the city's level.
Anyway I'd like to know what you think of my proposal. Questions, comments, and etc. let me know.