Cyrusfan, I see your point about needing to re-balance certain things if towns can't be adjacent. I completely agree. For one thing, they should probably generate much more gold. An extra +2, or perhaps outright doubling the +4 to a +8 would be in order. However, I definitely think if this system were implemented, that towns should require some amount of space in between them. Let me explain my reasoning.
What is a city in civ 4? A large collection of people who work the nearby area (the fat cross), and who exert their influence over an ever larger area (all the cultural area surrounding the city).
What is an improvement? Some sort of man-made (sometimes not man-made in the form of unique features) feature which improves the output of the land. Farms allow the land to produce more food, mines allow the land to produce more metals and stone which can be used for building things.
Towns though, stand out as seeming different. Unlike other improvements, like a city, a town also represents a large collection of people. Not as many people as a city, but many nevertheless. A town, which takes many turns to reach, probably has almost the population of a size 1 city.
Yet in civ 4, as in RifE, towns are just money making improvements. I could surround all 20 workable squares of a city with towns in this game. Yet, you would never see so many cities so close to each other, not even size one cities.
This idea would help more accurately represent how towns and cities work. Cities represent the center of government for a certain area. Not everyone lives in the city, but it is the center of government that controls how the surrounding lands are used. Towns, with this system, would act more like smaller population centers rather then just places where money is minted.
A farming town, which improves surrounding farms, represents a town where there is much knowledge on how to farm. Where farmers can come together and share ideas about weather, and crops, and animals ect. The effect is very local. Only the surrounding farms are effected.
Not all towns would act like this though. Take the university town for example. It represents a town where knowledge is highly valued. Perhaps it is the site where a famous university is located. As such, the bonus is not so local. An increase in the research of the nearest city. It could also have a significantly smaller research increase in the entire country in which it is located. This would be because the population on average is capable of learning more, and learning faster, when there are many universities in the country.
Similar lines of thought could be used to explain many different types of towns.
Jheral, your post has several things which have given me food for thought. I would rather what the town evolves into be semi-random. Perhaps use the great person system. Except different things would give your towns specialty town points (STP)
Say, a ST took 200 STP to evolve. The Amurites gain 5 wizard town points per turn just for being the Amurites. The town is also next to 2 farms and 1 mine, giving them 2 farming town STP and 1 mining town STP per turn. After 25 turns, the town evolves into a specialty town. It has a 5/8 chance of becoming a wizard town, a 2/8 chance in becoming a farming town, and a 1/8 chance in becoming a mining town.
The player would be able to somewhat control what the town becomes, while the town still evolves randomly. I think doing this has a few advantages over choosing what the town becomes via ability or spell.
Number 1, as nutranurse mentions, we want the AI to be able to use this system. If a town becomes a farming town primarily because there are farms around it, the AI will get the extra food even if it wasn't trying to get a farming town. The same goes for the other town types.
Number 2, it prevents certain types of bonuses, such as xp gain, from being stacked and becoming overpowered. Players would definitely build 4 wizard towns around 1 city, and have that city produce the entirety of the country's arcane force. An xp bonus, or any other type of bonus, can much more easily become overpowered if it is stacked then by itself.
Cyrusfan, to your most recent post where you say and I quote
I just think giving bonuses to all surrounding improvements of a given type is going to be overpowered.
I have several comments.
Number 1, if we give the bonuses to everyone, and if we make the other types of bonuses like the wizard town strong enough, then I don't think it would be overpowered.
The university town could have a bonus of +1000% beaker generation in the nearest city. To all who have a basic understanding of the mechanics of civ 4, this is better then +1 food to all surrounding farms. Likewise, if the bonus was +1% beaker generation in the nearest city, it would be obvious that it is worse then +1 food to all surrounding farms.
The trick here is to find the middle ground where the bonuses are about equal. Where you have to ask yourself which type of specialty town you would rather get.
To anyone who actually read all this wall of text, I congratulate you. Feel proud knowing you have at least 10,000 hp, since that's what I crit for.