The Eggman Empire (エッグマン帝国, Egguman Teikoku) is an Empire of scientists and robots. The Eggman Empire is never built, or seen. The Unleashed arc was the most recent to feature the Eggman Empire, although the Wisp Colors arc could possibly count in the form of his own company called "Eggman Enterprises".
In the Black Arms arc, the Eggman Empire is one of the factions that was fighting some kind of war both the world and Shadow (through even with their efforts to get him to align himself with them) along with GUN, Team Rocket and the Black Arms. When fighting for the Chaos Emeralds to get his memories back, Shadow is guided by Eggman, who communicates with him from a hovering TV-like apparatus.
Eggmanland (エッグマンランド, Eggumanrando; or known as Eggtropolis and also known as the Eggman Empire) is a land and home city 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.
The Capital of the Eggman Empire 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. However, while he himself may not be able to complete Eggmanland, while Sonic and his friends have continuesly thwarted his plans. In Unleashed Saga, Eggmanland does exist as one of the game's stages, created through the power of Dark Gaia and looking like a twisted mixture of a carnival and a factory. Eggman Fleet