An MMO is a massively multiplayer online game. It’s an umbrella term for games that support large numbers of players on a server, ranging from hundreds to tens of thousands at a time. This enables vast groups of players to play together, communicate, and sometimes attack each other in an open world. The term covers multiple genres, from high fantasy to sci-fi and more modern genres like [survival games](/c/survival-games).
MMOs share a few key elements, though not every game has these. It begins with the player and the choice of character, class, and faction. These are similar to an RPG’s selections, where the class will define the player’s overall abilities. Though players are almost always asked to select an overall race or faction, which will determine who players can play alongside, how certain NPCs and other players react, the story, and more. Many people will play as a different faction or race on a different server to fully experience the game’s story and world.
MMOs thrive on progress. Progression will affect a number of areas. A player will generally accrue experience points (XP) as they play. As their XP grows, so does their level. “Levelling up” is fairly universal, with each level presenting platters with a number of rewards that they can apply to their character, powers, weapons, and armor. Because of this, a player's friends might have the same class at level 1, but through customization, they could have very different versions of the class after a few levels. Player choice is expected in an MMO.
They are usually large, complex games in which a player is expected to spend a considerable amount of time, which usually requires a persistent open world for all the players to explore and play in. These worlds can be anything. Large swathes of fantasy landscapes, with continents and cities; galaxies or solar systems; or abandoned real-world cities, full of places to loot and hide. They are often designed so that each faction or race has safe spaces to play in where PVP is disabled or other factions simply can’t enter. Within these spaces, players can relax a little and explore the various vendors, tradesmen, and missions available.
It’s in these spaces that a lot of the game takes shape. A large element of MMOs is preparation. Players have to have something to do and the correct tools to do it. Quests and missions can be found anywhere in the world, but the bulk of them will be given to players by faction-based quest givers, who’ll send players out into the world to kill things, collect resources, and follow storylines.
MMOs are lively worlds (hopefully). Quests aren’t just a way of levelling up, but they help to introduce the larger game world. All around, players will be doing their own thing. Some are on the same quest, hitting the same rats (a trope of MMOs is to kill low-level creatures, sometimes just rats); others are crossing the world on their way to a bigger, better target. And with all those players around, good MMOs will have a number of cooperative and competitive modes.
[Co-op](/c/co-op-games) can be as simple as helping someone kill a creature while they’re out in the world, to complex world bosses that require dozens of players, each playing a part in the battle to bring them down. Raids are often performed with guild mates, who plan and execute a long run through a multi-level dungeon.
Competitive modes can be areas of the game world where PVP is switched on to allow for tense situations to structured PVP arenas where two teams battle it out.
The framework of an MMO can be applied to a number of genres. There have been classic, high-fantasy RPGs, shooters with hundreds of players, and space simulations with thousands of players on a single server. But they all have some elements that we’ve mentioned in the previous paragraphs.