The grievances system is interesting. I like that you can conquer parts of enemy civs in defensive wars without the rest of the world hating you until the end of time. One strange part is that as you conquer a civ, everyone gets angrier and angrier, until you wipe out the civ, there's no more negative modifier for grievances against another player, and suddenly everyone is happy again?
What? For me it's the opposite, wipeing a civ adds a ton of grievances on all civs against me. Capturing the last city of a civ is like -150 grievances with everybody