I agree that this would be very cool. It could be a seperate market from normal and alliances or nations could have laws on it and you could try to sell to nations with laws against it by hiding it in regular trades and each nation could have a kind of border patrol with varying effectiveness depending on the money invested. And you could smuggle heroin into a nation to decrease certain stats or you could sell weed to up your own stats. Something like that. The different drugs legal could have different effects on crime or health. Weed should make the population immortal by the way.