First off want to say I love the possibilities of this mod. It's the first mod i've seen that really does something to change the core gameplay.
Here is my take on how this could expand into something completly incredible.
First Stage:
Limit the selectable civs at start ONLY to civilizations from the ancient era.
Second Stage:
Make it so when a city rebels the following occurs-
1.) You get a popup asking which side you wish to take control of (your original empire, or the new emerging one)
2.) Choose from a pool of period specific (or ficticious but possible) civilizations. For example if your in the colonial age America could emerge.
3.) If possible make it so the new civilization is given access to the original civs unique units and buildings as well as their own. (If the British split into america, they get access to the Redcoat as well as the SEAL)
4.) New Civs certainlly would help
5.) Give newer age civs signifigant bonuses vs older ones.
What this would do is make older civilizations stagnate the older they become. Players would be forced to make a choice between becoming a newer more powerful civ, but losing most of their empire.... or keeping their older civilization and land, but becoming less useful the further along they go.
This would help emulate the progression of socieity as well...
Using this you could also allow for several "special" situations.
For example if a city with a religious capitol were to rebel a civ like the "papal states" could emerge. Declaring war on them would severly anger other civs of the same religion. Perhaps limit them by making them AI only (no choice to switch to them) and making it so they cant control more than 3 or 4 cities. Lots of things to consider here!
As for barbarians becoming civs... The current system sounds great already...but perhaps make some civs barbarian only. You could emulate the formation of the indian nations this way for example. If there is a landmass with no non-barbarian nations on it they could form there. Their technology is limited but they get huge growth bonuses, maybe access to a seperate tech tree or several unique units each? Lots of possibilities here I think. It would mean that you'd need plenty of units to conquor a "new world", but it would likely be 20+ warrior/spearman type units to one of your musketmen or knights or whathaveyou - Perhaps trading with these civs (or conquoring them) would be the only way to gain certain techs? If you were able to give them a unique tech tree perhaps they could have special wonders that would benifit you back home as well...
A few other ideas to consider with this sytem would be:
If you conquor a civ (of the same era?) you get access to their unique units and buildings (or if you conquor enough of their cities maybe? The exact specificiations would prolly have to be determined by playtesting)
Additional Mid/Late game versions of unique units. For example Modern Jannasaries, Mideivil Gallic Knights, etc. -- Make them not as powerful as the "native to era" units of the same period, but still slightly more powerful than the regular units. This could add a good dynamic to the game.
Take for example: You start the game as the Romans, you have a revolt and become the Turks, you conquor the Mongols, and later split into the Americans. Here is what you would have in late game:
You'd have your usual Navy SEAL UU. You'd also have a "Modern Jannasary" unit, A Modern Mongol UU (lol I forgot what their UU is ;-) ) , and a modern Legionaire type unit. You'd also have access to the unique buildings of each civilization. This would mean each empire would be radicly diffrent from one another. It would also give you pause as to weather you should become a more modern empire when the choice is available, or hope that another chance comes along with units/buildings you want more. It could even lead to you INTNENTIONALLY slowing research to prevent moving into a more modern era (Didn't the church do this in real life?) in hopes of a better revolution. Again lots to consider.
I think thats everything I can think of. I know it's a lot. If I had the skill i'd make some playtest models at the very least to see whats possible here. Let me know what you guys (especially mod developer) thinks. I can prolly make civs and possibly UU's (minus the graphics) if you'd need help with this, but it's pretty easy to do so you might work faster alone
Anyway great idea
-S
UPDATE:
Finally got some time to try it out. Your definatly on the right track. A few things to note however....
I started my game with 8 empires, huge map and marathon speed (as always). By the time I reached the first age jump, ALL of the civs had been used up already, and empires were revolting into the Barbarian State!
Perhaps a solution for this (aside from creating all new empires) would be to allow any leader to control any empire (this already kind of happens when you support a rebellion), and to make "duplicate" civilzations. Maybe make a script that would make variants of the same empire name: The Persian Empire, The Persian Caliphate, The Persian Republic etc. - Maybe make some of them possible only in certain eras. Maybe "light" revolutions could occur that would split an empire into two identical empires (in terms of UU's and buildings etc.) -- this would be pretty cool in midgame if you use my idea of progressivly gaining UU's etc. -- By midgame both you and the other side could have real revolts and have mostly the same things but slight diffrences (For example: You start as Roman, split into the English, have a "light rebellion" (say for example splitting into the English Empire, and The Kingdom of England), later you (Empire) split into America, and they (kingdom) split into China - You both would have Modern Jannasaries, and Modern Redcoats, but you would have the NAVY seal, and they would have... err I forgot the chineese UU lol
...
Just an idea on how to resolve that using the system I have above.
A few other (unrelated) things that I think would help the mod out greatly. First off I think the mod NEEEEEDS an inquisition system. Since religion causes revolts in many cases there needs to be a way to root out the evil religions causing the problem.
Second - More repressive governments usually lead to LESS rebellion rather than more - Depotisim should have the LOWEST chance of rebellion not the highest. The freer people are the more likely they are to revolt. As it stands now in early game your getting revolution messages every turn with the only way of solving is by invading neighbors... but what if your on an island map?
Third- make some updates to the tech tree. Perhaps theres an early age wonder that prevents rebellions until say The Calender is invented, and another one in each era. Maybe some buildings specificly help curtail the effects of a rebellion etc.
Fourth - While its not the focus of the mod perhaps increase research time a bit so people spend a little more time in each era. With so much stuff going on, even as is it can be a little overwhelming to advance so fast...even on marathon level.
Fifth - Add new colors for empires if possible. It gets confusing as all heck right now when you kill an empire and think you see it again later.
-S
Oh deer, just had another read through one of the readme docs and noted this:
