currently, im playing a game that has an implementation of PvP that i enjoy. in order for an encounter between two players both players must have the no PvP button off, then one must challenge the other. the only way for a duel to start is if the other player were to accept. at the end of the duel, the losing player doesnt lose anything accept all but one hitpoint. the player that wins the duel is penalized by not being able to turn off PvP for a certain amount of time.