PB Kim: The PK System is a sort of burdens for the developer in terms of considering balance not only between the player and the monster but also between the players. It might be very boring if there is only Player Vs Mob system and millions of players only slaying mobs everyday. The ‘troubles’ between players will give them some kind of ‘subject’ and it may bring a ‘fun’ for others in the game. Also the PK System is the one many of our users suggested continuously. Therefore, to challenging or searching for high-level player, people traveling around the Game Centers and looking for X Box Live. This can prove how much people enjoy the PK System.