Slaves should be apart of the population, that way nations could send in slave raiders to gather up population, slaves could have a benefit but also draw backs from a regular population, plus if your slave population was higher than your regular population there could be slave revolts etc... It would be complicated but would add another resource and or reason for nations to fight eachother or create economic hardships.
When is the resource aspect of BM coming into play anyways? I believe that will make the game ten times more fun and tactical/strategic.
