Blackhat City is an enormous flying city in Terra during its first age, and continuing into the Terra-Draco wars. Built on top of a 2 mile radius plate of black iron, it has a wide 'brim' around its circumference, and a number of uniformly tall, black buildings in the center; designed, it is assumed, explicitly to look like a black stove pipe hat. It contained what was both the largest and most advanced power source of its era, a large fusion generator contained in a pocket dimension. Its fall marked, and indeed was a part of the apocalypse that spawned the Third Age. It is related to, but not the same as, the Blackhats, an organization of combat-specialist holographists stationed in the city under the direct command of Domino Effect himself.
Formed by Domino Effect using advanced holography, Blackhat City was envisioned to be a worldwide, independent sanctuary for holography researchers, largely as a reaction to fearmongoring and sweeping legislation that was making all forms of such research criminal. Following its revelation, hostilities between him and nations worldwide threatened this ideal, at which point he created the Spare Change project and seeded holographic programs worldwide. These programs were used for both good and evil, but Domino, this city, and his enigmatic band of elites known as the Blackhats made every effort to maintain peace and punish misuse of the technology.
For many months following its inception, the city was empty, and often kept in storage (it maintains a pocket dimension as part of the function of its "engine"; this helps it hover and is used to warp around the planet). During this time, Domino did not have any political following and was widely regarded as an untrustworthy loose cannon at best, and a megalomaniacal terrorist at worst. However, following a sharp change in the political clime, Domino among others felt that many governments worldwide were threatening, kidnapping, torturing, or killing holography researchers, and stepped in repeatedly to save them and offer sanctuary. From that time, the city never sat in storage, preferring instead to warp over unpopulated areas or oceans if it had no legitimate destination. As time went on, it became clear both to refugees and outsiders that Domino had no ambitions of conquest or other malicious ends, and many joined either his city or his direct service of their own accord. The highest known count of the citizens of Blackhat City at any time was somewhere over 90,000.
The principle technologies of the city are its engine and power source, but they are by far not the most important or advanced. The city itself had the most powerful shielding capabilities ever known, and concealed many holographic weapons that made full use of the power source, though they were used but rarely, and only in self-defense. Additionally, it has holographic inhibitor arrays capable of shutting down unshielded holography within a radius of about a mile. It also had top-rate atomic-level fabrication, analysis, testing, and research facilities, along with large materials stockpiles largely acquired by disassembling garbage dumps. Its medical facilities, while added late, also would become top of their class. For the citizens living in it, food and water are unending and waste is completely handled, and various gardens and other places exist in extradimensional spaces.
When the city begins the process of warping, a disclike portal appears to one side of the city, and it begins to move into it using strictly horizontal slide. Depending on Domino's wishes, it may also rotate around the center of the city; this is usually the case when he, or the Blackhats, are at a place on the brim not facing the portal. The appearance of the portal on the other end is concurrent with a distinctive, low echoing boom and a number of electric pops and fizzles. (Domino has stated that the electric noises are a quality control issue originally, but that he likes the noise enough to not fix it.) The disappearance of the portal comes with similar electic spatter, but the noise is more implosive. The portal does not tend to give off much light of its own accord, although it is visible on dark nights, assuming that the other side of the portal is also dark. When warping to space, a modified form of the portal can be used to prevent air from bleeding around the corners of the city.
The city was also, on occasion, used to perform live concerts. Although Domino was not himself a musical performer, in conjunction with Mr. Stage, he became enthralled with the idea of communicating with and manipulating people by means of music. The latter was principally used only in combat conditions, but on occasion, Domino would simply park the city over a city, suburb, or other crowded region, play a selection of music (whatever entertained him at the time; usually inspirational music in genres like rock, metal, pop, etc), and he and his Stage magicians would choreograph their actions to it on the fly. Typically, this included a lot of lights, flying people, holographic graphics, etc. Although these events were impromptu and never announced in advance, and despite the imposing figure of Blackhat city, it is rumored (but never officially proclaimed) that these events never caused serious traffic accidents, fires, deaths, or other calamities.
The city is capable of travelling in hard vaccuum and surviving without outside resources or power, but it never did so for long periods. When it is in space, a crystalline dome covers the entire city, from the brim to the highest buildings. At Domino's whim, it has visited various places in the solar system, but (in offical canon) he never took it interstellar distances. Domino also maintained a few limited, manned research, mining, and storage facilities across the system, which helped recovery during the third age; however, he did not trust them enough to grant the occupants access to superior technology. While many of these facilities were only connected to Blackhat City by portal, some also had their own ships for emergency use.
The destruction of Blackhat City came at the end of the Terra-Draco Wars, during a time known as the Reign of Fire. One criminal, having in their hands the full codebase Domino Effect had been using to perform all of his effects, started a campaign to wipe out all people from Draco on both worlds in an effort to purify them; his weapons were post-nuclear grade, meaning that their expected yields exceeded the capabilities of nuclear weapons. An assault team led by Deus Exterra located the criminal, but were unable to make enough progress to kill him; against all advice, Domino Effect brought Blackhat City in to assist, and by doing so turned the tide of the battle. However, the city's shields were no longer impenetrable, given the weapons the criminal was using, and the city was destroyed. As part of that, the reactor overloaded and destroyed a 50-mile wide spherical crater; as an unfortunate consequence, the blast destroyed a large part of the Dragon System that is the source of power for the people of Draco. Between these two events, dimensional effects appeared worldwide that interfered with the minds of all living things, causing insanity in virtually all cases. This led to the Third Age, and very nearly caused an extinction of all life on both planets. Additionally, Domino Effect, Deus Exterra, Erika Exterra, and many others perished.