Eggmanland

In the fictional world of the Sonic the Hedgehog video game series, Eggmanland (sometimes known as Robotnikland or the Eggman Empire) is a land that Sonic the Hedgehog's nemesis, Dr. Eggman, often speaks of. In some continuities it is a land that he has already established; in others he only has plans for it. In most continuities, Eggmanland takes on the form of a technocratic dictatorship, with Dr. Eggman himself as the self-appointed Head of State. In general, as far as the social order of each continuity's Eggmanland spans out, robots and scientists employed by Eggman are granted greater social status than that of other Humans and Mobians.

Video games
In the video game and Sonic X continuities, Eggmanland does not actually exist; Eggman constantly strives to found it with various plans, several of which involve the use of Chaos Emeralds, the technology of his grandfather Gerald Robotnik, or both. In Sonic CD, Eggman temporarily succeeds in creating a complete "Eggmanland" in the future world of the Little Planet by altering the past - this dark future is mainly a bleak post-apocalyptic world with all of Eggman's robots being broken down and the scenery rusted and deteriorating, possibly suggesting that Eggman's desired utopia is doomed to failure.

Adventures of Sonic the Hedgehog
In Adventures of Sonic the Hedgehog, Dr. Robotnik takes over an amusement park called Mobiusland and renames this as Robotnikland, which he reprograms the rides to form a death trap. Sonic visits Robotnikland on his birthday as a trick by Scratch and Grounder.

Archie Comics/SatAM
In the Archie-published Sonic comics continuity and the Saturday Morning ("SatAM") ABC show it ran concurrently with, Dr. Robotnik had already conquered a majority of the planet Mobius. His state and regime had no official name, though his seat of power was the captured royal city of Mobotropolis, which he renamed Robotropolis and converted into a factory city to produce his legions of robots.

Later in the Archie continuity (SatAM was cancelled early into Archie's run), both the original Dr. Robotnik and Robotropolis have been destroyed. He has been replaced by a Robotnik from an alternate dimension, designed to resemble his Sonic Adventure era design, and along with the games, now refers to himself as Dr. Eggman (though sometimes still calling himself Robotnik to avoid continuity confusion). Eggman has now established the Eggman Empire, which covers select regions of the Planet Mobius as he rules from the city of New Megaopolis. This Empire is currently engaged in open war with the Kingdom of Acorn.

Sonic the Comic
In the continuity of Fleetway's Sonic the Comic, Doctor Robotnik managed to conquer all of the planet Mobius and establish a totalitarian regime when Sonic and his crew were catapulted six months into the future by the Omni-Viewer. He remained in power from Sonic the Comic #8-#100, ruling the planet first from the Special Zone's Egg Fortress and later from Citadel Robotnik in the Metropolis City Zone. Under his rule, Mobius was heavily industrialised and (deliberately) polluted. Citizens could be grabbed at any moment to be sent to the Badnik Processing Plants and Robotnik would regularly send Badniks to attack the Zones he was in charge of, just to show he could. Due to his constant targeting of the Emerald Hill Zone, the people were secretly evacuated to the Mushroom Hill Zone on the Floating Island.

In the milestone 100th issue of STC, all of Robotnik's computer systems and Badniks are wiped out by an electromagnetic pulse generated by Super Sonic. He never managed to regain his powerbase, despite the aid of the extra-dimensional Drakon Empire and he was eventually driven insane by his failures and imprisoned at last. The Doctor Robotnik Appreciation Tribe sprung up immediately after his defeat, campaigning to bring Robotnik back.

Sonic the Hedgehog: The Movie
In Sonic the Hedgehog: The Movie (also known as "Sonic Anime"), Dr. Eggman tells Sonic that he lived in the utopian city Eggmanland, but that a robot known as "Black Eggman" and his army destroyed his people and drove him into the dimension of Sonic and Tails, The Land of the Sky. In ADV Films' English dub, the land was referred to as Robotropolis and Black Eggman was known as "Metal Robotnik". Eggmanland itself appeared as a very modern city, complete with a giant light fixture in Eggman's likeness. The entire city is powered by the Egg Generator, a machine bearing Eggman's face, deep within the Doctor's base. Unlike the games, where Eggman wants to expand his empire, this version of Eggman seems content with ruling Eggmanland, and would rather simply destroy the Land of the Sky to make his empire the only ruling power in existence.