Guild Wars 2 claims to be unique in the genre[4] by featuring a storyline that is responsive to player actions,[5] something which is common in single player role-playing games but rarely (if ever) seen in multiplayer ones. A dynamic event system replaces traditional questing,[6] utilising the ripple effect to allow players to approach quests in different ways as part of a persistent world. Also of note is the combat system, which aims to be more dynamic than its predecessor by promoting synergy between professions and using the environment as a weapon,[7][8] as well as reducing the complexity of the Magic-style skill system of the original game. As a sequel to Guild Wars, Guild Wars 2 will feature the same lack of subscription fees that distinguished its predecessor from other commercially developed online games of the time, though a purchase is still required to install the game.[9]