Originally popularised in the 1960s, megastructures are a staple of science fiction. Theoretical feats of engineering at a planetary or even stellar scale, they have been the subject of speculation, novels, films, and a few video games.
Megastructures range from the impractical but technically possible to the outright fantastical. The term is vaguely-defined, though a unifying factor in all is that they are engineering projects of immense scale. Some are well-known, such as Star Wars’ Death Star, while others are more obscure, such as the ‘Beanstalk’ space elevator in Fantasy Flight Games’ Android setting.
The archetypal megastructure is the ringworld. First suggested in Larry Niven’s 1970 novel Ringworld, it is a vast space station constructed in a giant loop around a star, 1.6 million kilometres in diameter — roughly the same size as Earth’s orbit around the Sun. The inner surface of a ringworld is open but habitable, as it possesses its own atmosphere. There have been several adaptations and variations of the conceptual ringworld, from the even larger Alderson disk proposed by Dan Alderson, the enclosed topopolis (or ‘cosmic spaghetti’), and smaller orbitals and Bishop rings, which do not circle a star. The smallest variation of the ringworld was the Stanford torus, proposed as a theoretical project by NASA in 1975, which would constitute an enclosed circular habitat in orbit around the Earth. These designs have shaped our concepts of the future for much of the last half-century.
Aside from the work of Niven, ringworld-type megastructures have appeared in a wide array of fiction. The orbital first appeared in Iain M. Banks’ Consider Phlebas (1987), while the space station in Neill Blomkamp’s 2013 film Elysium bears a striking similarity to the Stanford torus (though like a larger ringworld it sustains its own atmosphere without needing to be enclosed). In games, the Halo series by Bungie Studios and 343 Industries has perhaps the most well-known example of ringworld derivatives in its titular Halo Array, a series of orbital habitats which double as superweapons. Created by the advanced ‘Forerunners’, they serve as primary locations for many of the games and were designed to study and prevent the spread of the parasitic Flood. During development of the first game, Halo: Combat Evolved (2001), the setting was originally to be a different form of megastructure known as a ‘globus cassus’, or ‘hollow world,’ but over the course of developing the game it was changed to a ringworld, then an orbital, with Niven’s Ringworld being cited as inspiration for this decision.
Other envisioned habitable megastructures include ecumenopoli and interstellar arks. An ecumenopolis is the theoretical final extent of urbanisation; a city spanning the entire surface of a planet. Perhaps the most well-known fictional ecumenopolis is the planet Coruscant in the Star Wars franchise, a major location in the film Revenge of the Sith (2005) and which has appeared in various games based in the Star Wars universe, such as the Battlefront series (2004-2017) and Star Wars: The Old Republic (2011).
Meanwhile, interstellar arks are conceptual spacecraft capable of housing and sustaining hundreds of thousands of people to ensure survival over long space journeys. Also known as ‘generation ships’ (meaning they are home to multiple generations of people), they are viewed as a plausible method of colonising other planets or surviving a catastrophe that rendered Earth uninhabitable. The idea has appeared commonly in science fiction, including the film Pandorum (2009) and the game Elite Dangerous (2014). They are often used to caution against over-industrialisation; in the 2008 Pixar film WALL-E, the remaining population of Earth live on an ark which will supposedly return home one day, but in truth has abandoned the planet due to intolerable levels of pollution.
The first ark appeared in the 1933 novel When Worlds Collide by Philip Wylie and Edwin Balmer, in which it was constructed to avoid the imminent destruction of Earth, though it only carried forty humans rather than the thousands later arks would. In games, Mass Effect: Andromeda (2017) features an ark as its main setting, destined for the Andromeda galaxy with the mission of finding new worlds to colonise. Amplitude Studios’ Endless Space 2 (2017) features a civilisation of zealous aliens called the Vodyani, who are forced to live aboard arks after they depleted the scarce natural resources of their homeworld. This ark-bound existence is carried through into the game’s mechanics: most factions must build colony ships and send them to uninhabited planets in order to expand, while the Vodyani must instead construct ark ships which can exploit the resources of an entire system at once. Should the Vodyani find a better location to settle, they can simply move the ark ship there instead of needing to spend time and resources on a new ship as the game’s more conventional factions would.
Another type of megastructure, and one with a great deal of versatility, is the Dyson sphere. An idea which originated in Olaf Stapledon’s 1937 novel Star Maker, the name came much later, in 1960, when physicist Freeman Dyson wrote a paper titled ‘Search for Artificial Stellar Sources of Infrared Radiation’ discussing a similar idea. The Dyson sphere is a theoretical solution to the problem of increasing energy requirements of an interplanetary or interstellar civilisation. Stapledon and Dyson suggested that, when energy requirements exceed the capacity of a single planet, a vast structure could be built around a star to harness far more of its energy than ever reaches a planet. Similar to the ringworld, there are a few variations of the Dyson sphere concept — including the Matrioshka brain, which uses the collected energy to power a gigantic computer; and the stellar engine, which converts the star’s energy into thrust, allowing the entire solar system containing the sphere to become mobile.
In fiction, Dyson spheres are amongst the most common megastructures. Niven wrote about Dyson rings, another variation of the Dyson sphere, in Ringworld, and Isaac Asimov mentioned them in the short story ‘The Last Question’ (1956). Farthest Star (1975) and Wall Around a Star (1983) by Frederik Pohl and Jack Williamson feature a Dyson sphere with an inhabited exterior, where the climate and wildlife are delightfully alien. More recently, Marvel Studios’ Avengers: Infinity War (2018) featured a Dyson sphere used to power the forge in Nidavellir, based on one of the Nine Realms from Norse mythology where the weapons of the gods were created.
In games, the Halo series once again makes use of these hypothetical structures. ‘Shield Worlds’ are a series of small spheres built around artificial stars. Like the Halo Array, they were created by the Forerunners — but their purpose was to protect organisms from the destructive capabilities of the Halo Array, so that when fired it would not wipe out the Forerunners along with the Flood. A significant portion of Halo 4 (2012) takes place on and within one of these Shield Worlds.
One game in particular stands out for its use of megastructures. Paradox Interactive’s Stellaris (2016) is a strategic sandbox, giving players total control over their species and civilisation from a governmental to a genetic level. Whether dictatorship or democracy, reptilian or robot, there are a wealth of possibilities in the game, including the restoration or construction of a huge variety of megastructures. In a game’s opening stages players have a good chance of encountering a ruined megastructure leftover from an ancient precursor, or meeting a ‘fallen empire’: a civilisation so ancient and advanced they no longer care to take part in galactic politics and warfare, but who possess fully-operational megastructures. As a player’s technology improves throughout the game, they will gain the ability to rebuild ruined megastructures, construct new ones of their own, or even build up a fleet capable of taking a fallen empire’s megastructures by force. While some of the megastructures are easily recognisable, such as ringworlds, ecumenopoli, and Dyson spheres, Stellaris also includes several unique megastructures such as ‘matter decompressors’, which extract minerals from black holes, and ‘gateways’, linked portals which can be used to instantaneously travel vast distances. Large artificial habitats can even be created to act as pseudo-planets. Stellaris is a game which doesn’t just include megastructures — it gives the player total control over them and what kind of role they will play in their empire.
However, it’s clear from the examples mentioned above that megastructures are more common in books and film than they are in video games. Partly this is down to their size: from the perspective of the player in a first-person shooter game, does it matter much whether the landscape you’re traversing is a naturally-occuring planet or an artificial one? An asset the size of a planet is only meaningful in gameplay terms at the grandest of scales; which is probably why, of the games listed above, several are in the ‘grand strategy’ genre.
Narrative is different from gameplay though, and here megastructures potentially have more relevance. An inconceivably massive megastructure kept shrouded in mystery, like the Halo Array, is that much more compelling and intriguing than a simple landscape, however improbable. This is part of the Big Dumb Object trope, covered in our roleplaying supplement in this issue.
Megastructures are perhaps the ultimate manifestation of a civilisation’s achievement. In science fiction, they give us a vision of how a post-Earth humanity could survive — but they’re more than that. Few of science fiction’s creations inspire as much awe. In storytelling, they serve as the logical endpoint of technological hubris and perhaps the zenith of what we think we as a species could one day achieve.