''Terminal World'' is a sci-fi novel by author Creator/AlastairReynolds. It's a stand-alone story, distinct from his usual ''Literature/RevelationSpace'' [[TheVerse universe]]. Taking place thousands of years into a [[CrapsackWorld bleak future]], the novel concerns the [[AfterTheEnd last remaining city of mankind]], the strange reality warps around it that limit the [[TechnologyLevels level of technology]] people can build, and a [[TheExile doctor's exile]] from that city into the wastelands outside.

The story begins on Spearpoint, a gigantic tower made of some long-forgotten indestructible material. On a long spiraling path winding up its sides is a city that has persisted for thousands of years. Out of the heart of Spearpoint emanates the "zones"; areas where the fundamental laws of reality seem to vary, limiting the kinds of technology that are able to exist within each zone. As such, Spearpoint is divided into distinct neighborhoods, depending on the main technology that is used within them. At the bottom is "Horsetown", where only the most basic, dirt-simple tools can function. Further up is "[[{{Steampunk}} Steamtown]]", where steam-based technology is possible, and "Neon City", where the technological level is on par with TheFifties. Further up still are more progressively advanced zones, culminating at the very top of Spearpoint with the "[[CrystalSpiresAndTogas Celestial Heights]]", where [[{{Transhuman}} posthuman]] [[GodGuise Angels]], their bodies thrumming with [[{{Nanotechnology}} nanotech]], fly through the sky.

The story follows a pathologist named Quillon, who works in a morgue in the Neon Heights. He's known as a bit of an eccentric, requesting the odd Angel corpse that has fallen from the higher levels to Neon Heights. Little do his colleagues know, he has a dark secret: Quillon himself is an Angel in disguise, sent to infiltrate the Neon Heights as part of an experiment to test the limits of Angel bio-engineering. Normally Angels will die if they leave their zone, since the nanotech in their bodies stops working, but Quillon and his original team had been altered to survive in the lower zones. However, the mission went awry, ending up with Quillon having to kill two of his partners. Now he spends his time trying not to draw attention to himself, hoping to stay relatively hidden in the lower tech zone; no one suspects his true nature, and he intends to keep it that way.

Then one day another Angel falls to the Neon Heights. Mistaken for dead, it's taken to Quillon [[WakingUpAtTheMorgue whereupon the "dead" angel wakes up]] and delivers a warning: get out of Spearpoint while you still can.

Now on the run, Quillon enlists the help of a [[TheLadette guide named Meroka]] in order to leave Spearpoint and flee into the wastelands beyond. Beyond Spearpoint, where the zones extend into vast geographical areas and [[TheApunkalypse roving bands of savages]] known as "[[SkeletonsInTheCoatCloset Skullboys]]" roam the land, raping and pillaging anyone they can find. Out there, Quillon and Meroka discover a woman with an astonishing ability: she's a "tectomancer", one who has the ability to [[RealityWarper shift the zones]].

After a devastating "zone storm" that nearly destroys Spearpoint and alters the landscape of reality, threatening society with collapse, Quillon and Meroka must seek out the assistance of the Swarm, a zeppelin-based former military branch of Spearpoint. With Swarm's assistance, they hope to return to Spearpoint with the tectomancer and restore the balance of the zones.

* ActionGirl: Meroka. Despite being described as quite dimunitive and young looking (Quillon nearly mistook her for a child at first), she's an utter badass who wears a BadassLongcoat.
** Young looking is debatable. The story is implied to take place on Mars, which makes Quillon's "anywhere from 10 to 15" years old remark equivalent to 20-30 Earth years. This is actually one of the first hints of "Earth's" real identity.
* AfterTheEnd: The world is slowly dying from an impending ice age, with the remaining societies constantly scouring the world for fuels. Some great disaster eons ago created the zones and has since seemingly doomed mankind to a slow extinction.
* AndManGrewProud: The disaster that caused the zones to come into existence occurred over ''ten thousand years ago''; you better believe that the descendants have come up with various myths and legends about it.
** The parable about the brothers Soul/Spirit and Fortune/Opportunity certainly counts. While the way it's presented in the story seems like a fairly fantastical, exaggerated creation myth, reading between the lines neatly explains the setting of the story: [[spoiler:The names refer to the martian rovers, implying the story actually takes place on a terraformed Mars, not Earth]].
* BadassGay: Meroka is stated early on to be a lesbian, and is quite the badass.
* BaldWomen: Kalis, whose head is shaved to display the tectomancer mark on the back of her head. [[spoiler:It's fake, designed to distract attention from her daughter's real mark]].
* BrainFood: Vorgs/want/brain. Give/vorgs/brain. Vorgs/need/more/brain.
* BurnTheWitch: A significant danger for tectomancers.
* CataclysmBackstory: Along with AndManGrewProud above. The world is filled with the relics of ancient advanced technologies that were rendered useless when the zones were created. The origin of the the whole mess has been mythologized into a book called the "[[DoesThisRemindYouOfAnything Testament]]", which superficially resembles Literature/TheBible but actually relates (via various [[FutureImperfect time-distored parable and metaphor]]) the history of the world prior to the zones.
* CrapsackWorld: Moving between the different zones causes chronic disorders in the neural system, the entire planet outside of Spearpoint is a wasteland full of carnivorgs, Skullboys, and the paranoid, isolationist Swarm. If you are from a high tech zone and try to leave the city, you die a horrible painful death unless you're doped up on anti-zonal drugs. The world is cooling, crops are starting to fail, and there's insufficient trees to heat up the lower city. Then...[[spoiler:[[FromBadToWorse it gets worse]] when the great zone storm hits, plunging Spearpoint into ruin]].
* {{Cyborg}}: Tulwar is a steampunk cyborg. The carnivorgs count as well; they were once fully mechanical, but have adapted to integrate living tissue into their composition.
* DieselPunk: Swarm, whenever they happen to be in a zone that supports diesel engines (which is most of the time, as this is the territory they try to stick to).
* EarthAllAlong: [[spoiler:Inverted. It's heavily implied that the planet the story takes place on is actually a terraformed Mars, not Earth, despite the characters referring to it as such]].
* EnforcedTechnologyLevels
* FanOfThePast: Ricasso, the leader of Swarm, is curious about history and has dedicated part of his life into researching/exploring the history of the world. This is noted as being somewhat eccentric of him; most the other characters in this CrapsackWorld are too busy trying to survive than to try and learn more about the world.See the ScienceIsUseless entry below.
* ForbiddenZone: The Bane, a zone in which functionality is so restricted that no living thing is capable of surviving. Sure enough, the heroes end up having to cross it.
* HideYourOtherness:
** Quillon has to keep getting his constantly re-growing "wing buds" amputated in order to keep on passing as human. This becomes an issue when he's forced to leave Spearpoint.
** Not only that, but his eyes being to turn an unnatural blue - not just the iris, but the ''whole eye'' - forcing him to wear sunglasses to keep his cover.
* HollywoodTourettes: Meroka, caused by her constant trips across the zones. Crossing the zones causes subtle changes in brain chemistry, with repeated trips causing symptoms like this.
* InSeriesNickname: Several characters only call Quillion by the nickname "Cutter".
* JustifiedTitle: ''Terminal World's'' planet is succumbing to a slow, inexorable death as the winters are growing longer and harsher, and the forests around Spearpoint are slowly thinning out. It also has a second meaning: [[spoiler: The world is a ''Terminal'' world as in ''aircraft terminal'', with an interstellar portal under its surface, reached by the tunnel that runs down the core of Spearpoint and its counterpart in the Bane.]]
* LookOnMyWorksYeMightyAndDespair: The part when the main characters, along with Swarm, discover [[spoiler:the ruins of a Chinese civilization]] deep in the Bane; the landscape is littered with the remains of various technologies, and at the center is [[spoiler:another great tower nearly identical to Spearpoint, along with a gigantic spaceship crashed near it]].
** Also, to a lesser degree, Spearpoint itself. One of it's nicknames is "The Godscraper".
* MainliningTheMonster: The world has been divided up into differing areas of technology, where the laws of reality are literally different from one are to the next, limiting how advanced certain items can be in certain areas. For the people of this world, traveling ''between'' these areas involves suffereing from the debilitating "Zone Sickness" that, in severe enough cases (or too fast of a transition between different zones) can kill. Fortunately, creatures called Carnivorgs can synthesize a medicine that alleviates the sickness...''un''fortunately, as their name would suggest, the Carnivorgs are vicious carnivorous cyborgs who [[BrainFood harvest the brain matter]] from the people they capture.
* MarkOfTheSupernatural: All tectomancers have a large red birthmark in the shape of a six-pointed star on the back of their head.
* MechanicalEvolution: How the Vorgs came to be. They are thought to have begun as basic robots with adaptable AI. When the zones were created, the robots that happened to survive by being in higher-tech zones where forced to scavenge for supplies to keep themselves maintained. Eventually, either though some kind of glitch (or, more likely, a depressingly coldly-logical decision), the robots began harvesting organic material and incorporating it into themselves.
* MedievalStasis: At least 10,000 years have gone by with virtually no technological or social progress. "Science" is an unknown word.
* TheMutiny: One is planned against Ricasso. [[spoiler:But it fails]].
* {{Nanotechnology}}: The angels have nanotech in their bloods.
* OrganicTechnology: Certain technological relics have persisted through the ages that are somehow able to survive in different zones, since organic material weathers zone transitions better than tech.
* OurAngelsAreDifferent: They're bio-engineered humans.
* OurWormholesAreDifferent: [[spoiler:The finale hints that Spearpoint and its twin in the Bane were used as wormhole generators by the ancient, technologically advanced civilization that created them in order to colonize the stars. Catastrophic failure while perforating reality led to the zones.]]
* RayGun: The Angel Gun which Quillon briefly wields.
* SchizoTech: [[JustifiedTrope Justified]] in that reality itself changes between the zones, limiting what technology can exist in certain areas.
* ScienceIsUseless: The attitude of most people in this world, due to its general {{crapsack|World}} nature and the limitations of the zones. Why bother trying to research new technology when it won't work in your particular zone anyway?
** Also combined with ScienceIsBad when Spatha, Ricasso's rival, plans to use his knowledge of Ricasso's science experiments as blackmail against Ricasso. His plan was to expose Ricasso's "eccentric" ideas to whole of Swarm, with the hope that they'd see his hobby as not only a waste, but potentially ''dangerous'' due to the fact that he keeps Vorgs locked aboard his ship.
* SequelHook: Suffice to say that if a sequel never materializes a ''lot'' of questions will go unanswered and plot points - including ''the main one'' - will remain unsolved.
* ShootOutTheLock: Quillion tries this with a pistol, and fails. Meroka then tries with a volley-gun and succeeds.
* SpaceElevator: Ricasso speculates that this might've been the original purpose of Spearpoint. Later on he abandons this hypothesis [[spoiler:when they discover the second tower in the Bane. It's nowhere near the equator, which is where a SpaceElevator would have to be located]].
* StarScraper: Spearpoint. The upper levels are so high as to be nearly outside the atmosphere. One character in the novel speculates that it might've been (the bottom-most part of a) SpaceElevator. Also [[spoiler:the second tower discovered within the Bane]].
* SteamPunk: Certain zones will only support Steam-based technology, so naturally these zones are characterised by many SteamPunk related tropes.
** There's actually a neigborhood in Spearpoint literally called "Steamtown".
** Swarm verges into this at points. Many of their airships having various kinds of backup engines, in case their normal engines fail due to crossing a zone.
* SympatheticMurderBackstory: Quillon murdered his Angel cohorts in his backstory. It was cold-blooded, but done in revenge because they murdered his love interest first, covered it up, and were planning on murdering him as well.
* {{Whatevermancy}}: The Tectomancers, who have mental control over the borders between the different zones. Spearpointers don't even believe they exist, thinking they're simply myths. The superstitious denizens of the world outside Spearpoint regard Tectomancers as akin to witches, to be feared and killed whenever discovered. Getting accused of being a Tectomancer, even if you aren't, [[BurnTheWitch is a death sentence]].
* TreasureChestCavity: The angel which warns Quillion to flee has the pieces of an advanced weapon surgically embedded inside its body for Quillion to extract after its death.
* TrenchCoatWarfare: In her introductory scene, Meroka opens her coat to reveal a sub-machine gun, a revolver, an automatic, a blunderbuss, a crossbow, and a varied assortment of knives.
* WakingUpAtTheMorgue: The angel who brings a message to Quillion.
* WingedHumanoid: The angels.
* YouCantGoHomeAgain: [[InvertedTrope Inverted]], in that you can't really ''leave'' home. Whatever zone you're born in becomes your natural zone, as your brain develops in that zone's conditions as you grow up. Going to a different zone requires the use of "anti-zonal" medication, which you have to take for the ''entire time you're out of your zone''. In other words, choosing to live somewhere else other than your natural zone involves constant medication.
* ZeppelinsFromAnotherWorld: Swarm, featured prominently on the cover of the novel, is a mobile city of zeppelins.