Or make them dependent on heroes. Where to found a new city you need a hero to appoint "Lord" and each hero can only be Lord of one or maybe two cities. Similar to a feudal system's fiefdoms.  

I actually really like the lord system idea.  It fits the original idea for the game doesn't it.

Sarcasm or compliment? Hopefully a compliment as I was just trying to help. I love talking through ideas and options and want to make SD products better. I've been an SD customer for a long time and plan on being, but if that's sarcasm it seems unnecessarily harsh...

I most certainly did not detect any sarcasm. From the looks of it, had you mentioned this during beta of the game, Frogboy would have implemented it as a mechanic.

It looks like genuine appreciation....though only Karma would tell for sure.

I doubt it's sarcasm too, tho given he has Derek and Soren you'd imagine they would have thought about that already...

Anyway not to harp on it but that's another thing Warlock had, and got right IMO. Just add nerve stapling and you're good to go

That first one seems unfun.

The second one, just build a new city or an outpost to prevent that.

yes!  i thought about trying to mod this a long time ago.  remove pioneers and just let each champion found 1 city (like sovereigns).  incorporate the champions name into the city name to enhance the story.

Number one.... I kinda already seen it before through civ 4 in different form , economy maintenance based expansion. As long as you keep your economy in good shape and growing you can keep on expanding although newly founded city is a burden on your economy until it grew to some degree to the point where it makes you money then you can plant another city again .You also had options to form an colony but I never exercised that power because i'm a dictator. Plus AI sucks at fighting anyways.

One drawback to the expansion technology is the capture cities problem. As I capture cities am I required to raze the cities if the number of cities is larger than the number of cities that I can maintain? Not that I don't mind that you can only have X cities until you research expansion techs. I don't claim to have a good answer to address this issue, but I'm curious what situation would be good for this situation.

You can only keep conquered cities if you have a hero who is a commander (base benefit of the class) or a warrior that has a new "Conqueror" trait selected at level-up in the conquering stack.  Once the city is conquered, the army and hero are immobilized in that city for 2 turns per level of the city + 2 more turns if the capital.

If you conquer a city without an available hero with a corresponding ability it burns itself to the ground (razes).

I am also in favor of linking city building to the fame/hero mechanic.  I would make it where you could choose either of the two heroes or a free pioneer unit instead.  

So, it boils down to mass genocide, if I cannot support the number of cities. I guess I'd have to be an evil evil man when conquering the world.

I suppose there could be a mechanic to say that the populations could transfer back to your cities... of course the slave trait would have to be adjusted to give a larger production bonus for larger cities, indicating slave labor.

In Warlock, you were able to convert excess cities to Free Cities that would not count towards the maximum city number limit. They provided some small bonus (either gold, mana or fortification), but could not construct buildings / units, and could not be converted back to full cities.

There was also a penalty on productivity for cities that were of a different race, which posed an interesting moral and gameplay dilemma (do you raze a Free City of a different race to unlock its full long term potential by getting your own settlers over there, or do you make do with the short term gain of a high level Free City? Cost of settler being already provided, which isn't trivial given it takes about 13 turns to recoup that cost alone).

Sorry if I sound like a broken record but I thought that aspect of Warlock was mostly well done.

I like the current system the best. I never really have a problem with high unrest. I just don't go out and conquer a dozen cities in a row. I take 2-3 and then build up my infrastructure to support them. Prisons and Oyx Thrones keep my global unrest down, and putting governors in new acquisitions allows me to develop them while their conquest penalty drops. Then I just move on to the next 2-3 cities. I think its a great system. If you can conquer dozens of cities in one go the game is probably over and your just messing around. Just force the AI to surrender and play at a higher difficulty. 

This is assuming you're playing as a Fallen empire, correct? For those without these options, unrest becomes much more of a battle to juggle.

Going back to my suggestion regarding a cap on cities you can manage, there's nothing to say it needs to be controlled exclusively via technology. I could easily see quests increasing the cap you can manage. I could also see where each champion you field increases that cap by one, etc. I think the goal with unrest is to prevent city spam. It isn't a perfect system, as ParrottMath points out the implications. I do like how Warlock allows you to convert it to be an independent city, though independent cities aren't currently a part of LH.

In its current form, you spend time managing a system that scales unrest by building things or stationing champions to reduce the unrest. I'd rather balance my resources between growth, money, production and research without the overhead of unrest, too. Perhaps it's a necessary evil to have it, but if there's a way to change it to be less indirect and more understandable, great!

I do not mind the general city cap, although it does limit a playing style. This of course could easily turn out to be a boon for certain civs. Civ X has double the number of allowable cities. Civ Y has about half the allowable cities... This could play very well in making a unique game world. Although, on the whole this would feel very gamey on the whole of it.