MU Online like most MMORPGs, players have to create a character among nine different classes and to set their foot on the MU Continent. In order to gain experience and thus to level up, a players needs to fight monsters (mobs). MU is populated by a large variety of monsters, from simple ones like goblins and golems, to frightening ones such as the Gorgon, Kundun or Selupan. Each monster-type is unique, has different spawn points, and drops different items. Outside of a duel, PvP fighting is possible but discouraged. When one player attacks another, a self-defense system is activated, in which the attacked player may kill the aggressor within a time limit. Self-defense is also activated when a player attacks an Elf's summoned creature. Outlaws have disadvantages during game play, depending on their Outlaw level.