How MMORPGs Work

A guy plays video games against brick wall.
In an MMORPG, you can team up with other players to take down bad guys who are far more powerful to tackle by yourself. Anastassiya Bezhekeneva / Getty Images

In today's world of big business and commercial culture, it's easy to feel like just another cog in the wheel. That's part of the allure of massively multiplayer online games (MMORPGs). In an MMORPG, you can team up with other players to take down bad guys who are far more powerful to tackle by yourself. You can make a name for yourself as a fighter, a healer or an artisan. Other people can rely on you to protect them from danger or even to save their lives -- in the game world, you can make a difference. You may even be a hero.

Of course, there's also killing monsters and taking their stuff.


Photo courtesy Consumer Guide Products

Two examples of MMORPGs: "World of Warcraft" and "Guild Wars"

Regardless of whether people play because of a sense of purpose or a desire to gather huge amounts of virtual wealth, in the past few years, MMORPGs have really taken off. Although they still don't make up the bulk of video game titles, the top-selling PC game in 2006 was Blizzard's MMORPG, "World of Warcraft" [source: NPD]. As of July 2007, "World of Warcraft" had about 9 million active subscribers worldwide [source: Blizzard].

­But the impact of video games like these goes beyond just the number of people who play. Newspapers and magazines have reported that participation in MMORPGs, especially in a leadership role, can look good on a person's résumé. Economists have studied in-game cash flows, looking for insight into the real-world economy. Health officials have even researched a plague that happened only in a virtual world in the hope of learning about how a disease becomes an epidemic.

All of this academic work is possible because of one common trait of MMORPG worlds -- they're immersive. To be successful, games have to allow players to think of an imaginary world as a real place with real rules. These rules cover everything from physics, like what happens when a character jumps off a waterfall, to etiquette, like what happens when one player in a group cheats others out of their loot.

In this article, we'll look at what it takes to create an immersive virtual world that allows people to move around and play within it. We'll also explore who plays these games and why. We'll begin with a look at where MMORPGs came from.

MMORPG Predecessors: Role-playing Games

One of the lizard-like Iksar from
One of the lizard-like Iksar from
Image courtesy Sony Online Entertainment

Although there are exceptions, most MMORPGs are set in worlds that have science-fiction or fantasy elements. Some worlds that appear in MMORPGs, such as the "Star Wars" universe and J.R.R. Tolkien's Middle-earth, existed long before their corresponding games did. Others are derived from other computer games or invented from scratch.

The worlds themselves can be vastly different from each other, but game play is usually similar from world to world. Basically, human players create virtual characters. These player characters (PCs) can interact with each other and with characters that the computer controls -- these are non-player characters (NPCs). There are different types, or classes of PCs, such as warriors, rogues, mages and healers. The different classes come with different sets of skills.


As PCs move through the world, they kill monsters and complete quests. In the process, they gain experience, which allows them to progress through levels, or level up. As characters level up, they get physically stronger and gain access to better skills, weapons and gear.

This basic style of game play was present in MMORPGs' early predecessors -- the tabletop role-playing games (RPGs), such as "Dungeons & Dragons," that debuted in the 1970s. In these games, a rulebook outlines everything from character creation to combat progression. A game master (GM) or dungeon master (DM) uses the rules to structure the game. He or she gives the players tasks, hints and bits of information designed to move a story forward. In theory, the story -- and the game -- can go on forever, but often the GM creates a campaign, or an arc of events that gives the overall story a little direction.

An elf wields her bow in SOLAR, a Georgia LARP.
An elf wields her bow in SOLAR, a Georgia LARP.
Image courtesy Jennie Breeden/Geebas on Parade

Today's RPGs are similar to those from 30 years ago. Players sit together in a room and describe what's happening in an imaginary world, using dice or other tools to determine whether characters are successful at what they're trying to accomplish. The progression of the story and the development of the characters in it are the heart of the game.

Some players take tabletop RPGs into the real world. In live-action role playing games (LARPs), players physically act out the actions of their characters, including participating in simulated combat with props and padded weapons.

After the development of home computers, it didn't take long for people to turn these low-tech, in-person games into computer games. Next, we'll take a look at the digital predecessors to MMORPGs.­

MMORPG Predecessors: Computer Games

Logging on to LambdaMOO:
Logging on to LambdaMOO:
Screenshot taken by HowStuffWorks staff

The first computerized role-playing games didn't have many of the bells and whistles of today's 3-D games. Text-based role-playing games, like multi-user dungeons (MUDs), took the idea of multi-player role playing to the online world. Particular types of MUDs include MUD object-oriented (MOO) and MUSH games. In games like these, lines of text describe the game world for multiple players.

Computer role-playing games, from classics like Sierra's "Space Quest" series to the forthcoming "Fallout 3," use animation and sound to recreate a game world. A player might create and control one character or a whole group of characters. In some games, players can customize their characters' statistics and appearance. In others, people choose from a selection of pre-made characters.


Classic 3-D role-playing games: one player, many floppies
Classic 3-D role-playing games: one player, many floppies
©2007 HowStuffWorks

But these games don't always support multiple players the way MUDs or tabletop games do. In some games, multiplayer mode is simply a multi-player copy of the single-player storyline. Instead of allowing one player or the computer to control multiple characters in the group, the multi-player mode allows multiple people to share the responsibility.

MMORPGs take this one step further. A vast number of players can create their own, independently controlled characters, each choosing to play in his or her own way. The first widely-popular MMORPG was "Ultima Online," which came out in 1997. In 1999, "EverQuest" made its debut ­and quickly gained such a reputation for being addictive that people nicknamed "EverCrack." Today's titles include "World of Warcraft," "Guild Wars," "City of Heroes," "EVE Online" and "Lord of the Rings Online." An MMORPG based on the world of the TV show "Firefly" and the film "Serenity" was announced in December 2006.

You could describe these games as vastly expanded versions of single-player RPGs or as MUDs with fancy graphics and sound. But in spite of the similarities, MMORPG worlds have some notable differences when compared to other games. We'll look at some of these in the next section.

The MMORPG World

In an MMORPG, you can't go back to a saved game if you die, but the game lets you come back to life.
In an MMORPG, you can't go back to a saved game if you die, but the game lets you come back to life.
©2004-2007 Blizzard Entertainment, Inc. All rights reserved. World of Warcraft and Blizzard Entertainment are trademarks or registered trademarks of Blizzard Entertainment, Inc. in the U.S. and/or other countries.

MMORPGs start out much like single-player RPGs do -- you buy a copy of the game and install it on your computer. But that's where the two game types diverge. With a single-player game, you can start playing right away. If you like, you can download and install a file called a patch that fixes any bugs discovered after the game's release.

In an MMORPG, patches are mandatory. The first time you open the game, your computer will download and install the necessary patches needed to make your game match everyone else's. Every time a new patch arrives, your game client will download and install it before you can play. You also have to register for an account, which allows you to log in to the game. Without an account, which typically costs around $15 a month, you can't play. There are a few games you can play online for free, but often you have to pay for better items or servers.


Unlike single-player worlds, MMORPG worlds are persistent. When you exit an ordinary RPG, the game world stops, and it starts again the next time you open the game. But an MMORPG world continues to function regardless of whether anyone is playing. For example, you might log out of the game surrounded by flowers that you intend to pick when you return. But if another player picks them all while you're gone, you'll log back in to find yourself in the middle of an empty field. If another player buys the only copy of a book that an in-game vendor has, you won't see the book if you stop by in the hope of finding it.

This persistent, ever-changing world also affects how you play the game. In an RPG, if you need to take a break to get a sandwich, you can just pause the game and resume play when you get back from the kitchen. If you're about to do something risky, you can save your game -- if your risk doesn't pay off, you can load your saved game and try again.

In an MMORPG, though, you can't pause, and you can't go back to a saved game. If you step away from the keyboard without moving to a safe location, you may come back to discover that your character was killed while you were gone. The game saves changes to your character as you go along, essentially overwriting each save.

Rather than allowing you to revert to a saved game, MMORPGs give you some options for making multiple attempts at dangerous tasks or undoing in-game choices. You can resurrect characters, although sometimes you have to pay a penalty, such as a fee to repair damaged armor. Sometimes, you can visit NPCs to change your characters' strengths or abilities.

However, some choices can't be undone. In most MMORPGs, you can't change your character's gender, race or class after you've started the game. If you decide you want to be a druid instead of a paladin, you have to make a new character. If you choose a reward from a quest and decide you'd like something different, you may not be able to try again for a different result. Fortunately, since MMORPG worlds tend to be very large, there are usually lots of opportunities for finding comparable -- or even better -- gear.

Killing monsters and collecting gear is only one part of the MMORPG world, though. On the next page, we'll look at what may be the most addictive component of an MMORPG -- the companionship of other people.

MMORPG Groups and Guilds

A large group of World of Warcraft characters in player-versus-player mode attacks the night elf capital city of Darnassus.
A large group of World of Warcraft characters in player-versus-player mode attacks the night elf capital city of Darnassus.
©2004-2007 Blizzard Entertainment, Inc. All rights reserved. World of Warcraft and Blizzard Entertainment are trademarks or registered trademarks of Blizzard Entertainment, Inc. in the U.S. and/or other countries.

MMORPGs are social. You can play parts of the game by yourself, but portions of the game require a group. Some of these groups are temporary -- they last only as long as it takes to kill a monster or clear a dungeon. Many games allow one person in the group to act as a leader. The leader can invite people to the group, remove people who are causing trouble and decide who gets what piece of gear.

Players can also join long-term groups called guilds. Guilds, also known as clans, kinships or crews, are usually groups of people who are working toward a common goal in a game. A guild might emphasize raiding -- progression through difficult dungeons with large groups of players -- or it might focus on helping lower-level players acquire gear and experience. Players may argue that one type of guild is better than another, but it all depends on what a particular player is looking for in the game. A player who wants to spend lots of time raiding may not be happy in a smaller guild that is mostly devoted to playing in small groups. Someone who wants to spend lots of time in player-versus-player (PVP) situations or battlegrounds may have more fun in a guild that includes lots of PVP enthusiasts.


Regardless of the size or structure of a guild or group, socializing tends to be a big part of playing an MMORPG. In some ways, the game is like a very big, very elaborate chat room. As players complete quests and fight their way through dungeons, they're often carrying on multiple conversations. Most games have lots of chat channels that allow players to talk only to their guild, their group or everyone in a particular zone. Some games have special channels for trade or for players who are looking for groups or guilds. Voice chat can take place through an in-game voice client or through a third-party program such as TeamSpeak and Ventrilo.

To some players, socializing is the most important part of game play -- some sources cite it as the reason why gamers spend almost twice as much time playing MMORPGs as other games [source: Caron]. But to others, raiding, fighting and getting better is the game's ultimate purpose. Next, we'll look at the basics of MMORPG game play.

Game Play

A group of players fights a dragon in Vanguard:
A group of players fights a dragon in Vanguard:
Photo courtesy Sony Online Entertainment

Getting around an MMORPG world is no small feat. Worlds tend to be large, and they're typically arranged into zones designed for players of different levels. When a new character enters the world, it starts out in a zone with low-level enemies and lots of quests. Once the player completes the quests, the character is usually strong enough to move on to a neighboring zone, which has slightly harder quests and enemies. While this gives most games a logical progression, some players find it repetitive and refer to the quest-and-level cycle as the level treadmill. Most games have several other features in common:

  • Classes and skills allow players to customize their characters. Different classes have different strengths and weaknesses, as do different skill sets.
  • NPCs offer quests, sell items, give advice and train characters in new skills.
  • Mobile objects, also known as mobs, give players opponents to fight. Mobs are any enemies that players can kill to gain treasure or experience.
  • Dungeons, also known as instances, give groups of players lots of mobs to attack and treasure to gather in a comparatively small amount of space. Dungeons aren't necessarily underground -- castles, space stations and even outdoor temples can all be classified as dungeons. Unlike the outside world, in which players must compete for monsters and resources, a group of players can have an instance all to themselves. The game gives each group its own copy of the dungeon, which no one else can enter.
  • Transportation methods, such as boats, space ships, mounts and teleportation devices allow characters to move over large distances in shorter amounts of time.
  • Containers, like backpacks and bags, let players manage their characters' inventories. Often, these containers display items in a grid. Some worlds allow characters to carry only a certain amount of weight. In many games, players can keep part of their inventory in virtual banks.

Each of these changes as players reach higher levels. In general, as players progress, they gain access to better abilities, higher-quality gear and faster transportation methods. But the game doesn't stop when players reach the level cap. Reaching the highest level often gives characters access to endgame dungeons. These dungeons are exceptionally difficult and sometimes require large numbers of players to complete. For some people, these dungeons, or raids, are the point of the game. But for others, the game is as much about socializing as it is about getting gear and loot.


Coordinating all of this activity requires lots of equipment. Next, we'll look at exactly how a computer and a server become a game world.

The Technology of MMORPGs

The realm status list for MMORPG Lineage II
The realm status list for MMORPG Lineage II
Screenshot taken by HowStuffWorks staff

There are several ways to coordinate the flow of data required to run an MMORPG, but the most common requires a client and a server. The client is the program that runs on your computer. The server is the machine -- or machines -- you connect to when you're ready to play.

A client is a combination of the playing board and the window used to view the game world. Nearly everything about the world -- including maps, landscapes and even what different mobs look like -- exists in files and databases on your computer. Your computer uses algorithms, or sets of rules, to translate these files into a representation of the game world and what's in it.


Your computer processes the game's sound and graphics. The game client on your computer also houses your user interface (UI), or the buttons and keystrokes you use to participate in the game. Some games allow you to modify your UI through independently-created add-ons. The client also tells the server where you are, where you're going and what actions your character takes.

A game client receives lots of information from the server as the game progresses, and handling it all requires lots of processing power. Game play can slow to a crawl for players with slow processors or poor graphics processing power, particularly in high-traffic areas. For this reason, many players find that they have to exceed a game's minimum system requirements in order to have a good playing experience.

The server has several responsibilities as well. Sometimes, these require input from the client, but in general, the server:

  • Compares where your character is to where mobs, players and NPCs are
  • Calculates whether a character is in range of the mob the player wants to attack
  • Notifies your client when you're being attacked
  • Calculates the probability of whether your attacks are successful
  • Reports how much damage or healing you do to you and the rest of your party
  • Notifies other players' clients when you damage or heal their characters
  • Instructs your computer to display a mob's death animation when you kill it
  • Determines what loot drops when you kill a mob

The term "server" is really a misnomer -- most MMORPGs require lots of servers. The most obvious, the world server, is where the game takes place. Sometimes, a world server is really several servers, and each one contains a particular zone or continent. Many games divide the player population into multiple world servers, also known as worlds or realms. On a physical level, different realms are virtually identical, and each has its own group of players, which can't often communicate with players on other servers. However, communities on each sever can develop distinct personalities. One realm might be dedicated to player-versus-player combat, while another might be primarily used by players who are interested in raiding.

MMORPGs require other servers as well:

  • A login server allows players to log in to the game and access the game world. Some games route players from multiple realms through one login server.
  • A chat server relays all the text players use to communicate with one another. A VoIP or voice server does the same for voice traffic.
  • A Web server allows players to access their account information. Some games display characters' statistics and gear on a Web page -- in these cases, the game's databases have to have access to the Web server.
  • Some games have their own game logic server, which performs all the necessary calculations related to game play and physics.

Game play is essentially an interaction between the client and the server. We'll look at exactly what happens next.

Client-server Interaction

Here's a basic look at what happens when a group of characters attacks a monster in a typical MMORPG:

Click to advance.

  1. The group approaches the mob. The groups' clients inform the server of where they are, and the server tells the clients which monster is nearby. The client accesses files relating to the monster's appearance and movement, which are stored on the computer's hard drive.
  2. A tank, or a character designed to be able to absorb a lot of damage, attacks the mob. The tank's client sends a message to the server, informing it of the attack. The server relays that information to the rest of the group's clients.
  3. The party's damage dealers, known as damage per second (DPS) or nukes, attack the mob. Their clients inform the server of what actions they take. The server calculates damage dealt and received and informs each client.
  4. The party's healer casts healing spells on the members of the party. The healer's client informs the server of what spells are being cast and on whom. The server calculates how much healing is done and relays the information to the rest of the party.
  5. The mob's artificial intelligence (AI) protocols determine how the mob behaves during the fight, and the server relays that information to the clients. If the party successfully kills the monster, the server informs each client to display the monster's death animation, which is stored on the computer's hard drive.
  6. A member of the party loots the monster to see what treasure it carried. The server selects items from a loot table at random and tells the clients which items dropped. If some of the players in the group have a quest that requires a certain item from the mob, the server instructs the client to display the icon for that item.
  7. The players, using text or voice chat, decide who will get an item according to the rules of their group or guild. They may use a built-in random number generator to determine who gets what item. If so, the server which distributes the results to all the other clients.
  8. The player who wins the loot clicks on it to pick it up. The client informs the server that the player has done so. The server informs the client to add the item to the player's visible inventory. It also stores the change in the player's inventory in that player's database entry.

These same steps can apply to just about any encounter in the world, whether it's with a player and an NPC, or a player and another player in a player-versus-player (PVP) environment. All of the information travels back and forth between the client and the server as packets of data. While many players rely on broadband Internet connections to handle the data, the transactions don't necessarily require a lot of bandwidth. Usually, the packets are small, but they come in bursts.


­More important than the speed of the player's Internet connection is how long it takes for information from your computer to travel all the way to the game server, and vice versa. If there are bottlenecks along the way, the player might experience latency. Latency is another name for a traffic delay. Sometimes, it's noticeable -- a player might attack a monster and have to wait a few seconds before the monster responds. In some cases, latency can significantly disrupt game play.

Developing an MMORPG requires more than just figuring out how to send these packets of data from one place to another. Next, we'll look at what it takes to create an MMORPG.­­

MMORPG Development

Most video games on the market today aren't MMORPGs. This isn't necessarily because MMORPGs don't sell well or because there aren't enough interested players. Instead, it's because MMORPGs take longer to develop, and they're more expensive to develop and run than other games. If an MMORPG doesn't take off, the developer stands to lose a lot of money.

There are several reasons for this. One is the size of the world and the amount of playable content -- or things to do -- that the game has to offer. MMORPGs have more physical land mass than other games. In other words, their worlds are larger. In addition, they take longer to play. Single-player RPGs take between 40 and 80 hours to complete. Other games can be finished in as few as 12 hours. But to be successful, and to be profitable for developers, MMORPGs have to have at least 500 hours of content. More content means a longer development cycle, and development can cost $10 million or more [source: IDGA, Persistent Worlds].


Writing is also a big part of MMORPG creation. For a newly-created world, developers often have to create a back story to make everything seem real. Even if developers are licensing an existing world such as Middle-earth, they may have to adjust the back story to make it relevant to the game. NPC dialog and quest text has to be logical, engaging and well written -- and since this makes up a substantial part of game play, there's a lot of text to write.

Physical features of the game world start with concept art and progress to 3-D renderings that will appear on the computer screen. Character movement comes from 3-D animation and from motion capture work done with actors in a studio. Developers also have to decide on the world's physics, even down to what happens when a character bumps into a table or a mailbox. All this has to be boiled down into information that can be stored in ones and zeros and expressed in computer languages like C++. Developers determine how to keep the game and its data secure using encryption and firewalls. Then, testers have to test the code to make sure it works.

But it doesn't stop there. Once the game launches, a whole new step in the development process begins. Players often make unexpected choices, leading to consequences that the game designers did not originally intend. The large influx of players into a finite server space can also reveal problems in the game that weren't evident during testing. On top of that, developers have to come up with new content after the game has launched to keep players interested.

Game companies also have to determine how to handle customer and technical support for the game. Since people will be playing the game 24 hours a day, staff members have to be on hand at all times to settle disputes between players. An around-the-clock support staff has to deal with everything from lost loot to griefing, or the deliberate use of the game to harass other players. Game companies also have to determine how to handle gold farmers, or players who collect vast amounts of in-game gold in order to sell it outside of the game world.

In spite of all that, MMORPGs have become a big business. Blizzard, the company behind "World of Warcraft," has announced its second expansion to the game. Popular games like "EverQuest" have spawned sequels. Developers have also announced entirely new games based on new or licensed worlds. Whether these games will take off remains to be seen, but since MMORPGs combine both technology and a social structure. Since both technology and social networks are appealing to many of today's computer users, it's likely that MMORPGs will remain a popular source of recreation.

To learn more about MMORPGs, RPGs and related topics, browse through the links on the next page.

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More Great Links

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