If you think about it, this also addresses anohter important issue which I already had a problem with. In the game, the best way to take over a city was extermination, it got you denarii and it was what made the people happiest. slavery was an alright option, some gold, some population and a little happy. But occupation was the worst! no gold, no extra population and very unhappy people. Just like this issue show, the whole city conquering process should be a little more complicated. it should depend on how similar your faction is to theirs as well as how similar the government of your capitol is to theirs. Exterminating should be the best option for say, Rome to barbarians but occupation should be a reasonable option for one successor/Greek nation conquering another.