ring around one of their stars, which is most likely around one astronomical unit in diameter. A completed version of this can also be found in another location. In computer games Space Empires IV and Space Empires V, the player can construct sphereworlds and ringworlds around stars. Dennis E. Taylor's 2020 novel Heaven's River features a Topopolis built around an alien system. Different segments of the structure are built with artificial climate and weather. Planetary and orbital scale Several structures from the fictional Halo universe: The original twelve Halos, seen in Halo: Cryptum, were 30,000 kilometers in diameter; a separate array of six Halos are 10,000 kilometers in diameter, with one of the original twelve later being reduced to this size in Halo: Primordium. The Lesser Ark is a 127,530 km diameter structure from which the Halo Array can be activated and capable of building 10,000 km Halos. The "greater" Ark, seen in Cryptum and Primordium, is capable of producing 30,000 km Halos. Onyx is an artificial planet made entirely out of Forerunner Sentinels (advanced replicating robots). At its core is a "shield world", contained within slipstream space, that is approximately one astronomical unit in diameter. The much smaller Shield World 0459, (approximately 1,400 km in diameter), is the setting for the latter half of Halo Wars. A third shield world, Requiem, is the primary setting for Halo 4. Requiem is an artificial hollow planet encased in a kind of Dyson Sphere. Halo 5: Guardians introduces a fourth shield world, Genesis. High Charity, the Covenant's mobile planetoid station. In the Doctor Who episodes The Stolen Earth and Journey’s End, a planet-sized space station known as The Crucible is built by the Daleks, a genocidal alien race, and facilitates the reality bomb, a weapon meant to erase the entire multiverse from existence. The Crucible also held enough Daleks to slaughter the universe they were in even without the bomb, according to The Doctor. In Sonic Adventure 2 and Shadow The Hedgehog, the Eclipse Cannon is a planet-destroying WMD built inside of the Space Colony Ark. Buster Machine III from Gunbuster. The Culture Orbital from The Culture. In the 2013 CGI anime film, Space Pirate Captain Harlock, the Jovian Accelerator is an ancient, Death Star-like Weapon of mass destruction that uses energy from Jupiter's atmosphere to create a large beam of intense light strong enough to destroy an entire planet. Sidonia, the