In fantasy settings magic and the mythic creatures are not abnormal, but a natural part of the world. It's normal to see wizards, the Anthropomorphic Personification of love, and even weirder fare sit down every third Tuesday for tea and biscuits (baked by tree elves, of course). Many things that are explained by physics in Real Life may even have completely different explanations in this world, such as The Grim Reaper going about ending lives (not necessarily killing, mind you), that fires are actually small (or enormous) imp-like beings, or that there are Nature Spirits that guide nature.
Then there's settings that take it even further. In a world where there are Magical Underpinnings of Reality, everything that happens in the world is attributable to a magical force, worker, artifact, or another explanation. Gravity? There's a gigantic god who is holding the world like a bucket and spinning to create centrifugal force. The stars? They're cute little lightbulb girls that are suspended on a gigantic scaffold. The changing of the seasons? The Fair Folk go about telling the plants to grow, bloom, or sleep. The sun? It's a giant lamp fueled by the laughter of good children, which is gathered by angels, so be good or the sun won't shine!
In short, most or even all the natural world works thanks to magical means. In a weird twist, they may even use industrial or scientific methods like worker shifts of gnomes who paint the leaves for fall, or machines that manufacture clouds. If this doesn't jive with science as we know it, there may be a Masquerade, or the magical aspect is only obvious in the Magic Land or Spirit World dimension parallel to the mundane world, but is no less important to the natural world. Some stories have the Magical Underpinnings of Reality act as Cosmic Keystones to the mundane world counterparts, so kidnapping the Maiden of Spring effectively stops spring from happening in the mundane world as well.
Essentially, everyone paints frost on the windows.
Compare Fantasy Kitchen Sink. See also World of Weirdness and "Just So" Story. Can be the result of enough Odd Job Gods. To populate this world usually requires authors make liberal use of Crossover Cosmology.
- In Nocturna, the nighttime world invisible to humans, fey beings go about ensuring that everything necessary for a normal (not necessarily "good") night's sleep happens. There's a writing department for dreams (and a cadre of tiny women who deliver and read them to you as you sleep), hair mussers that mess up your hair as you sleep, "composers" of nighttime sounds, and all lights are actually living beings. Stars are immortal doll-like lightbulb women who are suspended from a giant scaffold held aloft by a lighthouse; street lights are firefly-like workers in mining gear.
- In Moana, the demigod Maui is responsible for essentially every natural phenomenon that occurs. He pulled up the sky, made days longer by lassoing the sun, and even invented coconuts!
- In Stardust, stars in our world are the typical giant balls of gas (or meteorite), but on the other side of the wall they are immortal women who float in the sky and shine at night (unless someone hits them and knocks them down). A star crossing the wall turns into a lump of rock and metal.
- In Magical Legend of the Leprechauns, Trooping Fairies run nature worldwide, they manufacture leaves, make sure snow and spring and rain all take their due course, etc. But a war with the leprechauns distracts them from their duties, and so natural weather patterns worldwide collapse into chaos.
- Charmed: the loss of magic is an ecological disaster.
- The Whoniverse used to be like this, until the Time Lords exorcised magic and irrationality from the universe.
- Tom Holt's novel Here Comes The Sun is about a group of grumpy and bureaucratic beings responsible for ensuring the sun rises and the Nile delta floods and so on.
- In The Dresden Files the conflict between the Summer and Winter Courts of the Sidhe has a major impact on the change of the seasons and the overall climate of the planet. Global Warming is attributed to Summer having a slight advantage over the last few decades.
- In The Kingkiller Chronicle, the moon disappearing from the sky isn't caused by the moon being between the sun and the Earth, it's because when it's not in the sky, the moon is actually elsewhere, serving as the moon of Fae. This phenomenon may have been caused when a boy named Jax (Actually Iax, a long dead Namer, and purportedly the greatest of them all at the time.) learned the moon's name and partially trapped it in a box, hence the "Just So" Story of why the moon waxes and wanes.
- In the Mune Shinri (which the video game Oracle of Tao is loosely based on), reality is run by scientific laws, as much of the empirical world accepts. But behind thoses laws, the people keeping them working are various spirits, and a group of beings called Reapers.
- In the Incarnations of Immortality universe, magic is considered a natural force, along with gravity, magnetism, and a couple of others.
- In Pact, a theorized solution to the Fermi Paradox is that demons ate most of the universe. More locally, people are manipulated and guided at all times by small and nearly mindless spirits, who manipulate the connections between people and things to influence their actions and create a system of Karma where good deeds are rewarded and bad deeds are repaid.
- In The Stormlight Archive, many natural phenomena are caused not by physics, but by "spren", manifestations of concepts in the Spirit World of the Cognitive Realm that overlays the material world. For example, windspren accompany wind, gravityspren are responsible for bringing things down (or sideways, if you can control them), an ancient spren called Stormfather sends forth the highstorms and the hatespren can create an Everstorm.
Kaladin: [Gravity] is a law.
Syl: No, it's more like... more like an agreement among friends. We have to be consistent or we'll break your brains.
- Discworld: Cori Celesti, the home of the gods, is also the source of the magic which it turns out allows the Disc to exist in the first place.
- When they aren't causing trouble for Death and his granddaughter, the Auditors of Reality see to it that the universe operates as it's supposed to.
- Ciaphas Cain, THE HERO OF THE IMPERIUM, once mentioned the God-Emperor as keeping the galaxy spinning. Though it was a joke, there's probably Imperial cults out there that believe it.
- Journey to Chaos:
- Everything that exists, the whole of creation, is chaotic energy that has been diluted and solidified. This is what creates both physical matter and ethereal souls. Earth, air, food, flesh etc. everything is fundamentally energy from Lady Chaos. Mages who truly understand this gain an Enlightenment Superpower that enables them to return physical objects to mana which is a lesser form of chaos. In other words, disentegrate them.
- Every aspect of nature is represented by an avatar for the aggregate sentience of that element, which is responsible for making sure it runs smoothly.
- If reapers and sowers don't do their job, then life and death go out of whack.
- The general natural prosperity of a region is tied to its mana. The island nation of Ceiha is a wasteland because it doesn't have enough mana for plants to grow everywhere. Humans will basically feel less "alive" in areas of extremely low mana.
- In the Malazan Book of the Fallen, the goddess Burn dreams existence into reality and her body seems to literally be the world the characters live on. Consequences of her being hurt can be felt across the entire planet, such as earthquakes which are referred to as Burn's Pain.
- Done to Tartarus and back in Percy Jackson and the Olympians and its subsequent sequel series. Because All Myths Are True (so far, Greek, Roman, Egyptian, and Norse religions are all confirmed to exist and are real, and there's a reference to Jesus Christ as a real mythological being as well), there's a good chance you can point to anything and it was created by a god or through magic. Even historical figures aren't exempt, as many of them were either demigods or magicians. The sun is a giant ball of fire, and also the sun chariot driven by Helios and later Apollo, while Chinese celestial dragons also help out...
- A number of campaign worlds in the Dungeons & Dragons game have varying levels of this.
- The "Great Wheel" cosmology used in all settings though 2E (see Planescape), and in the core game through 3.5, posited that the "normal" worlds occupied a "Prime Material Plane", which floated in the "Ethereal Plane" and was composed of substance from the "Inner Planes" of four classical elements (air, earth, fire and water), two forms of energy (positive and negative), four "para-elements" formed by the intersection of true elements and eight "quasi-elements" formed by the interaction of primary elements with the two types of energy. There was also either a demiplane (2E and earlier) or plane (3E and later) of shadow. Beyond all this lay the "Astral Plane" and the "Outer Planes", which were based on belief and ideological concepts. Naturally all of these various planes were inherently driven by supernatural laws.
- In the Forgotten Realms, when the Overgod Ao got tired of the gods' misbehavior, he temporarily kicked them out of their home planes and forced them onto Toril as avatars. This caused extreme chaos since without the gods performing their jobs, the world didn't work right. Magic went wild, a different sun came up every day, the land twisted and warped, etc.
- The Ravenloft setting was based in "the Demiplane of Dread", a small pocket universe floating in the Ethereal Plane, apparently created and maintained by the mysterious "Dark Powers" as a holding pen for interesting evil beings. While some scientific laws are seemingly reliable, allowing for advancement up to roughly 18th Century technology in some Domains, these are always at the discretion of the Dark Powers, as is the behavior of magic.
- The Spelljammer setting was just made of this. Period.
- This is how Mythic Reality works in Nobilis. Everything has an anthropomorphic spirit. Everything. Your car, the chair you're sitting in, your teeth, etc. Mythic Reality is not "how things really work" so much as an alternative way of understanding the universe to "Prosaic Reality," the world of bound by laws of physics that we normally perceive.
- However, Earth is the only world on the Tree which has a Prosaic Reality. Mythic Reality is the default everywhere else.
- Being made forcibly aware of these magical underpinnings tends to drive mortals insane — Earth itself couldn't deal with the knowledge of a world in which the capricious whim of a god can wipe out the dominant lifeforms on the planet or transport rabbits from their peaceful undersea homes to the world of land, so it's not surprising that mere mortals can't, either. In 3e, the Locust Court allows victims to forget this knowledge and regain their sanity, if they can find it. Otherwise, those who can't learn to cope with the knowledge on their own are basically doomed to living with a view of the world that's accurate, but not rational or functional, and which causes them to (rightly) be considered insane by their peers.
- Exalted has everything — everything — in Creation made out of Essence, to the point that motonic theory (referring to "motes," the basic unit of Essence) is the setting's equivalent of atomic theory. Sorcery is the setting's equivalent of understanding physics to the point where you can tell them to sit down and shut up. In addition to that, everything in reality, from a single grain of rice to the sun itself, has a god that represents it. Causality is entirely dependent on the Pattern Spiders weaving the Loom of Fate properly.
- Unusually for this trope, the Magical Underpinnings Of Reality take up a managerial role. If you kill or traumatize the god of a river — which, as an Exalt, is pretty easy and usually exactly the wrong thing to do — the river won't disappear or dry up, but it will suddenly become far less predictable.
- Changeling: The Lost has it so that this is how Arcadia works. Every thing is a sentient force that requires you to make a Contract with it in order to gain its benefits. For instance, you need to make a Contract with Water in order to quench your thirst, though it can still drown you even if you haven't signed on. The Gentry gain most of their magic by forging these Contracts with the forces that technically hold the keys, and their changeling servants gain mastery of them by proxy.
- Oracle of Tao has the entire universe operate not through faeries, but through mechanistic laws (for instance, fire magic runs on principles of thermodynamics, meteorological principles for thunder and cold magic, et cetera). The Dark World works also works, but on entropy rather than energy. But the reverse is true, that everything from electricity to magnetism relies on faith, strong will, or emotions. This would all be normal, except mundane things like cellphones and ATM machines also run on magic, and the former can literally call God.
- In ZanZarah: The Hidden Portal, everything in the eponymous Another Dimension is powered by faeries (small magical mostly non-sentient creatures): stone faeries hold mountains together, nature ones make trees grow, water ones keep rivers flowing, etc., etc.
- The Elder Scrolls has this in spades. To note:
- The sun and stars are not typical balls of gas and plasma, but are actually holes punctured in reality by escaping spirits during the creation of Mundus (the mortal plane). They act as portals to Aetherius, the "Immortal Plane" and origin of all magic, which flows into Mundus through them (visible as nebulae) and acts as a Background Magic Field. The other parts of Nirn's Alien Sky include two moons which are not typical sub-planetoids, but are the rotting remains ("flesh divinity") of the "dead" god, Lorkhan. The planets? They're similarly said to be the remains of the other original spirits ("et'Ada") who participated in the creation of Mundus and now "dream that they are alive" through the faith of their worshipers. Outer space is likewise different, being an "infinite void" surrounding Mundus known as Oblivion. It is known to contain thousands of realms and other planes of existence, created and kept in existence by beings of immense power. The most notable are the Daedric Planes of the Daedric Princes, the et'Ada who did not make any sacrifices during the creation of Mundus and thus remain at full divine power. These planes are combination of Eldritch Locations, Fisher Kingdoms, and Genius Loci ruled with absolutely authority by their associated Princes.
- Time, particularly linear time, only exists through the will and power of Akatosh, the draconic God of Time and one of the Aedra, as well as the chief deity of the Nine Divines pantheon. Time originally did not exist, only coming into effect when Akatosh willed it so at the end of the Dawn Era. As such, it can be manipulated, leading to Time Crashes known as "Dragon Breaks", during which Reality Is Out to Lunch on Mundus. Historically, this has been most often caused by mortals using divine implements (the Staff of Towers, Numidium/Mantella, the Heart of Lorkhan, etc.).
- The laws of nature (the cycle of life and death, the seasons, etc.) and physics (gravity, etc.) are in a similar vein. Many of the et'Ada who created Mundus fully sacrificed themselves, dying while willing these laws into existence. These are known as the Ehlnofey (the "Earthbones"), and they can likewise be manipulated by mortals. (The Psijic Order and the Dwemer are renowned for this ability, allowing, for example, the Dwemer to Ragnarok Proof their creations.) Other Ehlnofey instead came together to make children, becoming the progenitors of mortal life on Nirn.
- The Powers That Be in Nexus War games are fighting the titular War for the right to reshape reality according to their rules, and everything works the way it does because some god wanted it to. The only reason we take things like physics, math, gravity or mortality for granted is because no one in the pantheon has a viable alternative to those things and one god wants them to happen very much, and so they remain constant in one cycle of the universe after another.
- Gunnerkrigg Court has the Moddey-Dhoo mentioning that Psychopomps' "clients" ensure that "the world continues to spin", though didn't clarify beyond this. Coyote elaborates in Chapter 39: The Great Secret. The minds of the dead affect how the world of ether works. The world the Moddey-Dhoo was referring to was his own. Mythical beings were myths first, then became real in the ether (Not necessarily in that order), though Coyote asserts that he does not actually exist.
- Unsounded has the Background Magic Field of the Khert, ostensibly the divinely created architecture by which the Gods maintain reality. It enables the Formulaic Magic system of pymary, collects and archives the memories of the dead (ostensibly to cleanse their souls for reincarnation), and reabsorbs rogue memories that have transformed into ghosts and snuck into the world. The fact that people can sail beyond the influence of the Khert, and that some elements of reality appear to be beyond the khert's ability to affect, is theologically dangerous ground.
- My Little Pony: Friendship is Magic: The ponies on that world do everything - wrap up the winter, wake up the animals, move the clouds to make rain, produce the rainbows and snow, make the autumn leaves fall - and their God Empresses are responsible for raising the sun, the moon, and the stars in general. In fact, the Everfree Forest is considered an unnatural site precisely because nature takes care of itself there.
- My Little Pony 'n Friends: The segment Moondreamers was about little space people (perhaps elves would be the best way to describe them) who were taught how to control the natural laws of the universe by the gods and by laws we mean everything. Their biggest duties were to create stars and collect thoughts from the ocean of unconsciousness and perfect them in order to give children good dreams. They used energy sources as well, they powered their machines by good feelings and those sources were called positrons.