Along with being real-time 3D, Uru had another ambitious goal: Uru Live, a Massively Multiplayer Online Game, like World of Warcraft, but with content released regularly as episodes similar to a TV series. Basically what Fortnite is today.
After completing Riven—the sequel to the bestselling Myst—in 1997, Rand Miller and Cyan Worlds, began development of what would become Uru: Ages Beyond Myst. Initially, the game was to have been called Myst Online and have been a multiplayer-only title, but game publisher Ubisoft pushed for a single-player dimension. The online component, branding Uru Live, did not ship with Ages Beyond Myst; in 2004, Uru Live was suspended entirely.
Instead, two expansion packs for the Prime game were made: Uru: To D'ni, which mostly introduces the (formerly) online content to those who never had a chance to join Uru Live, thus focusing mostly on the City of D'ni, and Uru: The Path of the Shell, which extends the story of Prime and consists of multiple Ages that had not been seen before.
In August 2004, Cyan in cooperation with fan-based communities opened up Until Uru, where privately-owned, fan-run servers could be used to meet as if they were in Uru Live. Cyan stressed, however, that this was not Uru Live: there was to be no new content, bug fixes, or updates of any kind. In fact, Cyan has revealed that "until" was actually intended to be two separate Sumerian words: "un," meaning people or community, and "til" (with an accented i), meaning to live or keep alive. Thus, "Until Uru" means roughly "the community keeps Uru alive."
Until Uru provided the same content and errors as the public beta test (known as the Prologue), with two exceptions. First, server administrators have additional access (for example, cones and barriers in the style the DRC had put them up can be positioned inside the caverns). Second, voice chat, which was unavailable in the Prologue for technical reasons, has been re-activated.
Dedicated fans kept an unsupported version of the game alive through Cyan-maintained servers. Online game distributor GameTap resurrected the game as Myst Online in 2007, but this version was canceled due to a lack of subscribers despite generally positive reviews. Cyan received the rights to Myst Online from GameTap and announced its intention to bring the game back.
In 2010, Cyan Worlds released the game free of charge, under the name MO:ULagain. It is currently hosted on Cyan-maintained servers.
In 2011, Cyan Worlds and OpenUru.org announced the release of Myst Online's client and 3ds Max plugin under the GNU GPL v3 license.
Much of Uru Live requires two people to play, and in some cases, a group of people.
A sublime garden Age with an autumn theme.
A small, sun-filled garden Age that complements Eder Delin.
A customizable arena once used by the D'ni for competitions. Explorers have created countless games and puzzles to be tried in this world.
A gigantic desert land that stretches a seemingly infinite distance. The mystic night sky and caves beneath the surface house the keys to unlocking the puzzle that was placed there. Houses a mini-game, with a soccer ball, and bone posts, that explorers can play soccer with. The name was released as meaning "Heavily Scarred".
An Age containing pods through which explorers can observe various areas of the planet. Known unofficially as "rehzihksehv", the D'ni word for "the pod age".
A gigantic jungle with many bizarre plants and animals. It can only be viewed from a special observation pod.
A frozen world punctuated by a breathtaking sea of ice. The ocean is home to colourful species of aquatic life, and must be viewed through an observational pod due to environmental risk.
A large desert with frequent sandstorms and an unusual large creature. The Age is viewed from a pod, possibly due to the bright sun and sandstorms.
A broken pod, thought to be under many feet of water. The pod only includes dim, red safety lights to light up the water filled interior.
Related: Myst Online: Uru Live - online version of Uru, kept (a)live
Related: DRC Site (via Archive.org) - original D'ni Resource Council site from Uru
Related: A Newcomer's Guide and Answer Sheet - good getting started resource