Massively multiplayer online role-playing game (MMORPG) is a genre of online role-playing video games (RPGs) in which a large number of players interact with one another in a virtual world.
As in all RPGs, players assume the role of a fictional character (most commonly in a fantasy setting)and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player RPGs by the number of players, and by the game's persistent world, usually hosted by the game's publisher, which continues to exist and evolve while the player is away from the game. MMORPGs should also be distinguished from their text-based relatives, sometimes called MU*s (more specifically MUDs, MUSHes, MOOs etc. depending on the codebase, which are generally free games based on an open source codebase.
MMORPGs are very popular throughout the world, with combined global memberships in subscription and non-subscription games exceeding 15 million as of 2006. Worldwide revenues for MMORPGs exceeded half a billion dollars in 2005,and Western revenues exceeded one billion USD in 2006.
Though MMORPGs have evolved considerably, and modern versions sometimes differ dramatically from their antecedents, many of them share some basic characteristics.
The majority of MMORPGs are based on traditional fantasy-themed game play, occurring in an in-game universe comparable to that of Dungeons & Dragons. Some employ hybrid themes that either merge or substitute fantasy elements with those of science fiction, sword and sorcery, crime fiction, but there are other themes like soccer, the occult, or other recognizable literary genres. Often these elements are developed using similar tasks and scenarios involving quests, monsters, and loot.
In nearly all MMORPGs the development of the player's character is a primary goal. Many titles feature a character progression system in which players earn experience points for their actions and use those points to reach character "levels", which makes them better at whatever they do. Traditionally, combat with monsters and completing quests for NPC's, either alone or in groups, is the primary way to earn experience points. The accumulation of wealth (including combat-useful items) is also a way to progress in many titles, and again, this is traditionally best accomplished via combat. The cycle produced by these conditions, combat leading to new items allowing for more combat with no change in gameplay, is sometimes pejoratively referred to as the level treadmill. The role-playing game Progress Quest was created as a parody of this trend..
Also traditional in the genre is the eventual demand on players to team up with others in order to progress at the optimal rate. This tends to force players to change their real-world schedules in order to "keep up" within the game-world. Though some titles recognize this trend as a problem and provide ways to progress within short, unscheduled periods of time, this is still widely criticized of games in the genre.
MMORPGs always allow players to communicate with one another. Depending on the other interactions allowed by the game, other social expectations will be present.
Many MMORPGs exploit their players' social skills and offer support for in-game guilds or clans (though these will usually form whether the game supports them or not).As a result many players will find themselves as either a member or a leader of such a group after playing a MMORPG for some time. These organizations will likely have further expectations for their members (such as intra-guild assistance).
Even if players never join a formal group, they are still usually expected to be a part of a small team during game play, and will probably be expected to carry out a specialized role. In combat-based MMORPGs, usual roles include the "tank", a character who absorbs enemy blows and protects other members of the team, the "healer", a character responsible for keeping up the health of the party, the "Damage Dealer," a character suited to inflicting damage, with less ability to resist large amounts of it, and a "nuker", usually a magic user, that has abilities that inflict large amounts of damage, but is the most physically weak compared to its counterparts. Additionally there might be classes dedicated to "buffing", using abilities that help oneself or a team by increasing their attributes or abilities, or "debuffing", using abilities to hinder enemies by lowering their attributes and abilities. Each game might have these roles, additional hybrid roles, or might eliminate them. Some players might enjoy one role over others and continue to play it through many different MMORPG titles.
Some MMORPGs also may expect players to roleplay their characters - that is, to speak and act in the way their character would act, even if it means shying away from other goals such as wealth or experience. Most MMORPG players never actually play the roles of their characters, however, and so this behavior is far from being the norm. Still, MMORPGs may offer "RP-only" servers for those who wish to immerse themselves in the game in this way.
Often titles will also feature Game Moderators or Game Masters (frequently abbreviated to GM), which may be paid employees or unpaid volunteers who attempt to supervise the world. Some GMs may have additional access to features and information related to the game that are not available to other players and roles.