There's an interesting thread on MMORPG about XSYON being a griefer's paradise. I agreed, and here is why:
What is the difference between "griefing" and normal PvP? The normal PvP game has a goal, with benefits to winning. For example, you may get "Realm Points" or something to spend on improving your character skills or gear. Or, you may be attacking or defending a thing, a keep for example, and if you win or lose it it has an effect on the game. For example, take the keep and everybody gets a bonus stat. Xsyon has nothing like this. There is no actual PvP in that sense, since there is no reward for winning and no loss when you lose.
Griefing is player-vs-player too, but the goal is purely to kill the player, there is no other reward. In PvP, I may kill you for a reason, in griefing, killing you is the reason. Xsyon is a griefer's paradise, since there is no normal PvP.