What makes a good Diplo map?

Hey folks,

I'm planning on making a Diplo map based on a homebrew world and I was curious what the general expectation of players going into a Diplo-style game would be. Is it mostly up to the players to RP as their faction while everyone strives for the same goal, or should there be unique victory conditions for different players? Could a lobby RP-ing a typical game on one of the Real World maps be considered Diplo, or is there more nuance to that?

Thanks!