The idea of barbarians (rebels) spawned by unhappy or resisting citizens sounds like it would bring an interesting new element to the game.
To cover the barbarian evolution, the barbarian units produced could be based on the infantry units of their respective time periods and civilizations. For example, if your civ can produce pikemen and you have a city in unrest, that city could lose population and pop out one or two barbarian swordsmen. (Perhaps they could be regular swordsmen who, when defeated, are enslaved and turned into workers. This could represent the culling of an uprising faction.)
But if a person pays attention to unhappiness or sets up governor control, riots could be easily avoided. This element could be given more relevence if applied to conquered cities.
If you take control of a city with resisting citizens then there is a chance for producing rebel units in the general area. If you capture an opposing civs city and that civs defensive unit is riflemen, then there is a chance resisting citizens could disappear and turn into rebel riflemen. It would reduce the population, making things easier once control is established, but you'd have to handle one or two conscript or regular units for each resisting citizen. It would be like a forced conscription on captured civ's cities.
This could potentially give opponents a troop advantage in wartime or make a citiy captured once more difficult to capture a second time. Maybe after these rebelling units recapture the city, two or three of them would remain as defence and the rest would rejoin the city population. After all, these aren't military personnel, just ordinary people looking to defend their homes.
So it doesn't give opponent civs and unfair advantage, this ability could apply to the player as well. If a player's city is captured and their are resisting citizens present, there is a chance they will disband and turn into military units under the player's control. I don't think the player should have control over this. The invading civilization would most likely try to break off communication and coordinated rebellious uprisings of any sort. Perhaps the Espionage tech could allow a player to have more control over this action, though. A new option could become available where a player could select resisting citizens in foreign occupied cities and turn them into conscript rebels. These rebel units could be allowed to rejoin the city population after the war. Potentially the rebels could also move to a different city and join the population as refugees.
I didn't play Civ2 too much but now that I think about it this element existed in that game to an extent. Captured cities would produce partisan units some of the time. I don't remember the circumstances that caused this but I know it happened a few times.
Anyway... Barbarian units spawned from cities seems like the type of unexpected thing to make me tear my hair out in frustration. And at the end of the day, isn't this what Civ3 is all about. Increasing baldness in the world.
