I was actually writing some ideas for a MMORPG like that. Basically, the entire region will be carved into territories. Each territory will have a NPC leader. Players can choose whichever territory they would like to live in. If these players are sick of the leader, they can kick him out and elect a new leader who will be an actual player. Player vs. Player matches will involve capture the flag and territorial conquests.

Territorial conquests:
Leader and army
vs.
Leader and army

Rules:
-Opposing armies have 2 rounds to defend their city and capture their opponent's city. If one amry wins the first and the other next, a tiebreaker round will be presented.
-Both leaders must put a city on the line.
-Winner owns the loser's city that he/she entered at the beginning of the match.

First match (Defend your city) Setting: Your City
(Opponent attempts to conquer yours)
(0 points for successful/unsuccessful defense)
(1 point for successful conquest)

Seond match (Conquer opponents city) Setting: Opponent's City
(Opponent attempts to defend theirs)
(0 points for successful/unsuccessful defense)
(1 point for successful conquest)

Thid match: (Deathmatch: Fight to the death) Setting: Your City
(1 point for the team that racks up the most kills)