Meridian 59 is an online computer role-playing game first published by the now defunct 3DO Company and now run by Near Death Studios. First launched online in an early form on December 15, 1995 and released commercially in September 1996 with a flat-rate monthly subscription, Meridian 59 is often credited as the first 3D graphical "massively multiplayer online game" or MMO.

Meridian 59, the first commercial, 3D massively multiplayer game, was developed by Archetype Interactive and published in September 1996 by 3DO. Meridian 59 was Archetype Interactive`s only product; Archetype Interactive was acquired by 3DO in June 1996. Archetype was run by Steve Sellers, Mike Sellers, and John Hanke, with Andrew Kirmse and Chris Kirmse filling key technical roles. Damion Schubert contributed to the design along with a team totaling 22 employees and contractors. The game`s technological base was initially inspired by Scepter of Goth.

The game was in an early beta stage in April 1996 when it was noticed by Kevin Hester and other game developers at 3DO. Trip Hawkins, CEO of 3DO, recognized the forward-looking value of the game and the company, and 3DO bought Archetype in June 1996. More than 25,000 players joined the game`s public beta that lasted up until its commercial launch on September 27, 1996, beating its next major rival, Ultima Online, by approximately a year. Although Meridian arguably holds the title as the first realtime three dimensional online role playing game, it lacks some features of its modern forebears. For instance, the ability to jump was not implemented as a function of character input. Any jumping required in puzzle solving is done by climbing an incline and falling from one platform to another. This is the same limitation that Doom suffered; the game used a similar engine written in part by the original developers. Due to restrictions placed upon level designers by the graphics engine, many of the maps appear to have similar limitations to Doom. For instance, unnatural sharp edges are common, as are short walls that are placed to prevent the (non-jumping) player from entering incomplete areas of the world. Tree-lines are duplicate image stamps ,similar to tiled desktop backgrounds, and environment sounds are short clips from readily available sound sources. However, the game contained may other features that modern games duplicate later: guilds had a dynamic voting system for changing leadership, customized sigils that appeared on shields, and guild halls that could be won or lost. There were also in-game bulletin board system (called newsglobes), a personal mail system that both players and NPCs could use to send messages, a political meta-game, and frequent expansions that expanded the world and gameplay options.

Prior to its release, the term "massively multiplayer" and the acronym "MMORPG" emerged in meetings within 3DO (beating out other monikers such as "large-n game"), as did the now-ubiquitous monthly subscription model. At the time, AOL was still charging per minute, though a change to flat fees was anticipated. The game received multiple awards, including the fantasy-role-playing game of the year for 1996. It has also had various updates throughout its life, each adding new monsters, spells, and areas. 3DO shut down the game on August 31, 2000 and it was re-released by Near Death Studios, Inc. in 2002. Near Death Studios was co-founded by former Meridian 59 developers Rob "Q" Ellis and Brian `Psychochild` Green. A new rendering engine was added to the game in the Evolution expansion on October 2004, offering an alternative to its Doom-based graphics. This expansion also included features like dynamic lighting, rebindable keys, mouselook, and other visual improvements.

Meridian 59 is a typical sword and sorcery setting where adventurers go out and fight monsters. In the game, there are few NPCs, with most of them static and unchanging. Most of the focus is on the activities of the players as they fight against the monsters in the land. The game is set in the 59th provincial colony of an ancient empire which explored the universe through portals in a magical nexus. However, several hundred years ago, something went wrong and the young frontier colonies in Meridian 59 were separated from the Empire. Now the land is in turmoil. Political factions fight for territory and power, monsters, trolls, orcs, and the undead threaten to destroy all life, and the magical nexus is in a flux, causing disasters across the land. Meridian 59 features six cities and towns: the rebellious mining town of Jasper, the royal city of Barloque, the thriving but troubled Tos, the peaceful farming village of Marion, the crossroads lake-side university town of Cor Noth, and the independent jungle island settlement of Ko`Catan. While there is evidence of ancient dwarves and some other high fantasy races, players can only play human characters.