What is the Metaverse?
The short answer: "It's the Internet, except you can walk around in it."
The long answer: "An Internet-like system, except using a three-dimensional world metaphor with which you interact using a three-dimensional virtual representation of yourself (see Digital Avatar) instead of a two-dimensional hyperlinked-document metaphor with which you interact by clicking links and buttons."
The trope answer: The Internet becoming Cyberspace for real and everyone knowing about it and interacting with it that way.
The advent of Second Life and its open-source equivalent, Open Simulator, may make this future arrive sooner than you think. Some might argue that it already has, what with real-world governments and businesses setting up shop in Second Life, people making real-world money entirely within Second Life, and successful experiments at teleporting avatars between the Second Life grid and various OpenSim grids. However, with the drastic dulling of the use of these services, the concept fell by the wayside for years... until projects like Oculus Rift and Janus VR started bringing it back.
This is a subtrope of Cyberspace where it's widely known and used as a replacement for today's Internet by the public at large, not just by a few lucky hackers, discoverers, or inventors' friends.
- Ghost in the Shell: Stand Alone Complex - See the episode where Major Kusanagi visits a chat room, for example.
- Mnemosyne has "2.0". We see it grow in importance over the course of the series.
- Serial Experiments Lain mixes this with an incredible amount of Mind Screw.
- Den-noh Coil, to a degree. Augmented Reality is more like it.
- Real Drive: from the same creator as Ghost in the Shell.
- Summer Wars has Oz, and its big brother, the Digimon movie Our War Game takes the same approach to the Internet. Superflat Monogram also has a similar Internet representation.
- The manga for Densha Otoko has a very primitive version of this, with round, dumpling-like users floating in a gray cyberspace and talking in text, as a representation for a chatroom.
- In The Matrix and its sequels, the Matrix is a "neuro-active simulation" which human minds are jacked into to keep them under the machines' control. It's a very convincing simulation of late 20th century civilization, except to those few that don't take to it and are sought out by the rebels to become redpills.
- The Sidebar Universes in Justina Robson's Living Next Door to the God of Love are a lot like this. Robson makes it difficult to tell where (or if) reality ends and virtual reality begins.
- The Infosphere in Dan Simmon's Hyperion. Also the Megasphere, the true home of the AI Core, and the Metasphere, aka the Void Which Binds.
- Nero Manson's Sex Drugs And Violence In The Future depicts "The Grid" as a metaphysical overlay of ASCII characters on the real world.
- Inscape in several of Karl Schroeder's book, especially Ventus, Lady of Mazes, and Permanence.
- Used on a massive scale in the Golden Age trilogy by John C. Wright.
- Used in the works of Kawahara Reki. The idea is just starting to pick up steam in Sword Art Online, but by the time of Accel World it's become commonplace. It helps that between the two series "diving" technology is miniaturised from bulky NerveGear headsets to the slim NeuroLinker collar, the latter also having an Augmented Reality function that essentially replaces mobile phones.
- Ready Player One has the OASIS - the Ontologically Anthropocentric Sensory Immersive Simulation - which specifically evolved out of an Massively Multiplayer Online Role-Playing Game to encompass all the others. Yes. ALL OF THEM. It's implied (or at least one could easily get the impression) that every fictional character and universe one could imagine (and everything from said universes) actually exists, though of course only a fraction of it is actually shown. Its source of revenue isn't even a subscription, but transport through the vast gamespace.
- In Unison Spark by Andy Marino, Unison is a social network that operates like this. Users access the virtual world by clapping their hands together. The protagonists, Ambrose Truax and Mistletoe, are trying to stop the new upgrade to Unison 3.0, which is more nefarious than it seems.
- The oneirochronon (literally, "dreamtime") in Aristoi.
- The titular RÉEL (the acronym is French for "real"), where every person on Earth has an individual account since birth. It allows an equal access to education, communication and entertainment.
- Hoshi and the Red City Circuit has Memspace, a computer-generated environment through which people's minds can retrieve data and interact with each other. People are legally required to have a Digital Avatar called a franca so that other people in memspace know who they are. Hoshi's looks exactly like her real self, but some people choose to look completely different.
- Caprica's holobands.
- In Whitewolf's Mage: The Ascension game, there's the Digital Web, and one faction is working on Reality 2.0 to boot.
- Shadowrun's Matrix. Not related to the movie.
- The d20 Modern book d20 Cyberscape addresses this.
- The Mesh in Eclipse Phase typically employs Augmented Reality instead of virtual but it's practically the same thing.
- Subverted in Digimon Story: Cyber Sleuth. EDEN at first seems to be this, to the point of the introduction's narration outright describing it as a metaverse. Midway into the game, it's revealed that EDEN was merely created in cyberspace, which is just Another Dimension between the Digital World and the human world. People's avatars are actually artificial bodies made of data that their mental data is transferred to.
- Mega Man Battle Network - The Internet has evolved into just this, except the avatars are independent, sentient entities instead of just virtual images of the users. Also, it's been extended into everything from water coolers to vases.
- The Nameless Mod: a meta example. The game (mod) is set in forum city-a fictional metaverse based on Deus Ex where player avatars are based on Deus Ex characters.
- Kid Radd has the digital protagonists living in the internet, which to them looks much like this trope.
- In Futurama, after clearing the Valley of Pop-Up Ads, you reach a huge metropolis where Google and Yahoo are in the big buildings. The porn sites are in the red light district.