From my point of view, there are
many people who do not like pvp (I personally love it) but I understand those
people who do not like it. You could do something similar like: Make PvP
optional, and give rewards to those who take it. If they kill a certain amount
of enemies, you can go for a cool title. You can make skirmishes, arenas, clan
wars. You could even build fortresses for each clan and wage wars trying to
destroy the enemies with catapults, etc.