As in all RPGs, players assume the role of a fictional character (often in a fantasy world), and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player CRPGs 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 are very popular throughout the world. Worldwide revenues for MMORPGs exceeded half a billion dollars in 2005, and Western revenues exceeded US$1 billion in 2006.
Character abilities are often very specific due to this. Depending on the particular game, the specialties might be as basic as simply having a greater affinity in one statistic, gaining certain bonuses of in-game resources related in-game race, job, etc.
Very often a player's character design will leak into other creative areas of their life, such as artwork, stories or attempting to keep the same general design in another MMORPG they might play.
In nearly all MMORPGs, the development of the player's character is a primary goal. Many MMORPGs 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 NPCs, 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, or 'grinding'. 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 sometimes forces players to change their real-world schedules in order to "keep up" within the game-world.
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 "DPS (Damage Per Second)," a character specializing in inflicting damage, and sometimes the "CC (Crowd Control)," a character who temporarily controls the opponent, such as the "NPC" (Non-Player Character), and making the opponent lose its control of actions and abilities. Other common roles include being a dedicated "buffer" or "debuffer", using abilities that affect the team or the opponents in other ways. Any given MMORPG might allow players to take on all of these roles, additional hybrid roles, or none of them. Despite the variability, some players might enjoy one role over others and continue to play it through many different MMORPG titles.
MMORPG's generally have 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.
As another example, in many older MMORPGs the fastest way to progress was simply by killing the same monsters over and over again, and as this is still common in the genre all MMORPG players know the process as "grinding". The importance of grinding in MMORPGs, and how much "fun" it contributes to the experience, is constantly debated.
MMORPG addiction, which has been a source of concern for parents, also affects the culture. Some players might look down on those who invest huge amounts of time into a game, while others might scorn those who can't put in the time to "play properly."
Some MMORPGs require payment of a monthly subscription to play. By nature, "massively multiplayer" games are always online, and most require some sort of continuous revenue (such as monthly subscriptions and advertisements) for maintenance and development.
Depending on the number of players and the system architecture, a MMORPG might actually be run on multiple separate servers, each representing an independent world, where players from one server cannot interact with those from another. In many MMORPGs the number of players in one world is often limited to around a few thousands, but a notable example of the opposite is EVE Online which accommodated around 20,000 players in the same world as of August 2007 and 41,690 users online in December 2007. Some games allow characters to appear on any world, but not simultaneously, others limit each character to the world in which it was created.
Although MMORPGs, as defined today, have only existed since the early 1990s, all MMORPGs can trace a lineage back to the earliest multi-user games which started appearing in the late 1970s. The first of these was Mazewar, though more would soon be developed for the PLATO system. 1984 saw a Roguelike (semi-graphical) multi-user game, called Islands of Kesmai. The first "truly" graphical multi-user RPG was Neverwinter Nights, which was delivered through America Online in 1991 and was personally championed by AOL President Steve Case. Other early proprietary graphical MMORPGs include three on The Sierra Network: The Shadow of Yserbius in 1992, The Fates of Twinion in 1993, and The Ruins of Cawdor in 1995.
When NSFNET restrictions were lifted in 1995, the Internet was opened up to developers, which allowed for the first really "massive" titles. The first success after this point was Meridian 59, which also featured first-person 3D graphics, although The Realm Online appeared nearly simultaneously and may be credited with bringing the genre to a wider player-base. Ultima Online, released in 1997, may be credited with first popularizing the genre, though Nexus: The Kingdom of the Winds was primarily responsible for mainstream attention throughout Asia which was released in 1996, about a year earlier than Ultima Online. It was EverQuest that brought MMORPGs to the mainstream in the West.
These early titles' financial success has ensured competition in the genre since that time. MMORPG titles now exist on consoles and in new settings, and their players enjoy higher-quality gameplay. The current market for MMORPGs has Blizzard's World of Warcraft dominating as the largest pay-to-play MMORPG, alongside earlier such titles like Final Fantasy XI and Phantasy Star Online, though an additional market exists for free-to-play MMORPGs, which are supported by advertising and purchases of in-game items. This free-to-play model is particularly common in Korean MMORPGs such as MapleStory and Rohan: Blood Feud. One exception, however, is Guild Wars, which avoids competition with other MMORPGs by only requiring the initial purchase of the game to play.
Since the interactions between MMORPG players are real, even if the environments are virtual, psychologists and sociologists are able to use MMORPGs as tools for academic research. Sherry Turkle, a clinical psychologist, has conducted interviews with computer users including game-players. Turkle found that many people have expanded their emotional range by exploring the many different roles (including gender identities) that MMORPGs allow a person to explore.
Nick Yee has surveyed more than 35,000 MMORPG players over the past several years, focusing on psychological and sociological aspects of these games. Recent findings included that 15% of players become a guild-leader at one time or another, but most generally find the job tough and thankless; and that players spend a considerable amount of time (often a third of their total time investment) doing things that are external to gameplay but part of the metagame.
Many players report that the emotions they feel while playing an MMORPG are very strong, to the extent that 8.7% of male and 23.2% of female players in a statistical study have had an online wedding. Other researchers have found that the enjoyment of a game is directly related to the social organization of a game, ranging from brief encounters between players to highly organized play in structured groups.
Richard Bartle classified multiplayer RPG-players into four primary psychological groups. His classifications were then expanded upon by Erwin Andreasen, who developed the concept into the thirty-question Bartle Test that helps players determine which category they are associated with. With over 200,000 test responses as of 2006, this is perhaps the largest ongoing survey of multiplayer game players.
In World of Warcraft, a temporary programming glitch attracted the attention of psychologists and epidemiologists across North America, when the "Corrupted Blood" ability of a monster began to spread unintentionally into the wider game world. The Center for Disease Control used the incident as a research model to chart both the progression of a disease, and the potential human response to large-scale epidemic infection.
Many MMORPGs feature living economies. Virtual items and currency have to be gained through play and have definite value for players. Such a virtual economy can be analyzed (using data logged by the game) and has value in economic research; more significantly, these "virtual" economies can have an impact on the economies of the real world.
One of the early researchers of MMORPGs was Edward Castronova, who demonstrated that a supply-and-demand market exists for virtual items and that it crosses over with the real world. This crossover has some requirements of the game:
The idea of attaching real-world value to "virtual" items has had a profound effect on players and the game industry, and even the courts. Castronova's first study in 2002 found that a highly liquid (if illegal) currency market existed, with the value of Everquest's in-game currency exceeding that of the Japanese yen. Some people even make a living by working these virtual economies; these people are often referred to as gold farmers, and may be employed in game sweatshops.
Game publishers usually prohibit the exchange of real-world money for virtual goods, but others actively promote the idea of linking (and directly profiting from) an exchange. In Second Life and Entropia Universe, the virtual economy and the real-world economy are directly linked. This means that real money can be deposited for game money and vice versa. Real-world items have also been sold for game money in Entropia, and some players of Second Life have generated revenues in excess of $100,000.
Some of the issues confronting online economies include:
Linking real-world and virtual economies is rare in MMORPGs, as it is generally believed to be detrimental to gameplay. If real-world wealth can be used to obtain greater, more immediate rewards than skillful gameplay, the incentive for strategic roleplay and real game involvement is diminished. It could also easily lead to a skewed hierarchy where richer players gain better items, allowing them to take on stronger opponents and level up more quickly than less wealthy but more committed players.
The cost of developing a competitive commercial MMORPG title often exceeds $10 million. These projects require multiple disciplines within game design and development such as 3D modeling, 2D art, animation, user interfaces, client/server engineering, database architecture, and network infrastructure.
The front-end (or client) component of a commercial, modern MMORPG features 3D graphics. As with other modern 3D games, the front-end requires expertise with implementing 3D engines, real-time shader techniques and physics simulation. The actual visual content (areas, creatures, characters, weapons, spaceships and so forth) is developed by artists who typically begin with two-dimensional concept art, and later convert these concepts into animated 3D scenes, models and texture maps.
Developing an MMOG server requires expertise with client/server architecture, network protocols, security, and relational database design. MMORPGs include reliable systems for a number of vital tasks. The server must be able to handle and verify a large number of connections, prevent cheating, and apply changes (bug fixes or added content) to the game. A system for recording the game's data at regular intervals, without stopping the game, is also important.
Maintenance requires sufficient servers and bandwidth, and a dedicated support staff. Insufficient resources for maintenance lead to lag and frustration for the players, and can severely damage the reputation of a game, especially at launch. Care must also be taken to ensure that player population remains at an acceptable level by adding or removing servers ("shards"). Peer-to-peer MMORPGs could theoretically work cheaply and efficiently in regulating server load, but practical issues such as asymmetrical network bandwidth and CPU-hungry rendering engines make them a difficult proposition. Additionally, they would probably become vulnerable to other problems including new possibilities for cheating. The hosted infrastructure for a commercial-grade MMORPG requires the deployment of hundreds (or even thousands) of servers. Developing an affordable infrastructure for an online game requires developers to scale to large numbers of players with less hardware and network investment.
In addition, the development team will need to have expertise with the fundamentals of game design: world-building, lore and game mechanics, as well as what makes games fun.
Some independent MMORPG projects are completely open source, while others like PlaneShift feature proprietary content made with an open-source game engine. The developers of Endless Online have also released development information with details about their coding.
The WorldForge project has been active since 1998 and formed a community of independent developers who are working on creating framework for a number of open-source MMORPGs. The Multiverse Network is also creating a network and platform specifically for independent MMOG developers.