I have never successfully pulled off forcing the AI into accepting my demands to become a vassal. Both weak, friendly, allied factions and ones I have all but annihilated have laughed me off as if they wouldnt benefit/avoid destruction. What are the conditions for this to be accepted? Does it even deserve a place in the game?

Also, what is your single favorite feature in Vanilla for gameplay/realism purposes? I have yet to try a mod but I'm hearing good things about it. Naturally the developers' description is biased, so I wanted to poll you folks. Thanks!