What Is an MMO?

Massively multiplayer online games, explained

Two gamers sitting at the table opposite each other with a crowd of cheering fans on the background.

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In video game vernacular, MMO stands for massively multiplayer online. MMO games, or simply MMOs, make up the most popular genre of the modern era. Learn what an MMO is, how they work, and what you need to play them.

What Is an MMO Game?

As the name suggests, MMO games are not designed to be played alone. While it's possible to play some such games offline, MMOs encourage cooperation and competition between players. For that reason, many MMOs function as social networks where gamers can chat with other gamers from around the world.

Even if you've never encountered the term, you've probably played or at least heard of an MMO game. Fortnite, FarmVille, World of Warcraft, and Minecraft all fall under the MMO umbrella. There are sports, racing, and fighting themed MMOs.

The History of MMO Games

Before MMOs, there were MUDs, or multi-user dungeons. During the 1970s, these primitive, multiplayer, text-based games ran on early internet servers. Most MUDs were role-playing games (RPGs) with mechanics similar to the board game Dungeons & Dragons, so it's no surprise that the first MMOs were also RPGs.

An MMORPG is a massively multiplayer online role-playing game. The line between MMOs and MMORPGs can be blurry, but the latter typically emphasize storytelling, world building, complex strategies, and item management. Of course, most MMOs include several of these features, which all derive from MUDs.

The MMO genre was exclusive to computer gaming until the mid-2000s when consoles began to include Wi-Fi capabilities. MMOs grew in popularity with the rise of smartphones and social media, both of which significantly lowered the barrier of entry for new game developers.

Characteristics of MMOs

To be an MMO, a game must have a "persistent world" residing on remote servers. Players connect to the server nearest to them so that they can interact with other gamers in real time. Even when the player turns the game off, the game keeps running indefinitely. Therefore, MMOs never "end," although some feature story modes that can be completed.

Most MMOs also feature virtual economies in which players exchange in-game currency for items. It's often possible to exchange real-world money for virtual money. Players can also usually trade items with each other.

MMOs are similar to multiplayer online battle arenas (MOBAs), which include games like League of Legends and Hearthstone. The major difference is that MOBAs lack a persistent world.

While games like Mortal Kombat 11 include several elements of MMOs, they are not considered part of the genre because the multiplayer player features are secondary to the core gameplay.

What You Need to Play MMO Games

All you need to play MMO games is a reliable internet connection. There are many MMOs that are free to play while others require either a flat up-front cost or a paid subscription.

More Examples of MMO Games

The following games have, at one point, had thousands, and in some cases millions, of simultaneous players:

  • Club Penguin
  • DC Universe Online
  • EverQuest
  • Final Fantasy XI
  • Final Fantasy XIV
  • RuneScape
  • Second Life
  • Star Wars: The Old Republic
  • The Sims Online
  • The Elder Scrolls Online
  • Ultima Online
  • World of Tanks
  • World War II Online