Other sites use modified versions of phpBB that allow for a certain level of interactive roleplaying and are what is commonly referred to as "forum-based roleplaying". Interactive gaming can include player versus player features, a form of currency for making purchases in stores, and non-player characters such as monsters that must be fought to gain levels and experience points. However, these features are more prevalent in games that are not forum-based. Advancement in such games is usually dependent on live chat, multiplayer cooperation, and fighting as opposed to taking classes or simply posting to earn points for one's "house"; like at Hogwarts, players in forum-based games are sometimes sorted into a different group distinguishing different values within a person.