World Tree is a tabletop role-playing game set on [[WorldTree a tree thousands of miles tall]], whose branches are fifty miles wide and hundreds of thousands long. Eight "prime" species build a civilization with extremely widespread magic under the visible influence of [[strike:nineteen]] seven-plus-twelve gods. Other intelligent races live in their shadow; the primes know that the world was created for the primes' benefit with themselves as a backdrop; some non-primes disagree. The world is very different from ours, from basic physics (no electromagnetism, no air pressure) to materials science (lots of wood, little metal; it's a tree), to cosmology (seven meddling gods visible in the night sky). The game focuses on adventurous primes who face monsters, intrigue and other parts of life on the Tree.

The prime races and the gods that created them include:

* Herethroy (Creation): Peaceful, pastoral, six-limbed insects of three distinct genders who vary between farming and wielding [[{{BFS}} three-handed swords]].
* Cani (Control): Chummy dog-folk with complex social structure and instinctual loyalty.
* Rassimel (Healing): Obsessive, intelligent raccoon-people.
* Orren (Knowledge): Shapeshifting mercurial otterfolk with a tendency to go hyperactive under stress. Described as having "species-wide ADD." Explicitly labeled the JackOfAllStats.
''Less Common''
* Khytsoyis (Destruction): Sloppily-designed, floating heptapods (that is, seven-tentacled octapi) who pound things with [[DualWielding triple-wielded]] clubs.
* Gormoror (Control+Destruction): Mighty bears with a magic honor sense. ProudWarriorRaceGuy is their hat.
* Sleeth (Change): Non-anthropomorphic big cats with telekinesis over flesh-based objects and the VerbalTic of speaking in present tense.
* Zi Ri (Sustaining): Cat-sized, immortal, hermaphroditic, hovering dragons with fire resistance and weak fire breath.

The game exists as a [[ paperback sourcebook]] and an [[ in-game novel]] plus the semi-canon, in-character [[ diary of "Sythyry"]] written by one of the authors (which [[ inspired]] [[ several]] [[ imitators]]).

The rules are largely skill-based, with most of what characters can do being summed up in their skills, together with ten stats and a point-buy attributes system. Magic is handled using an Arts system (similar to ArsMagica), with all magic made up of Nouns and Verbs combined in various ways. As the classic example, a fireball would use "create" and "fire".

For those interested, a rather good review can be found [[ here]].

!WorldTreeRPG provides examples of:
* AboveGoodAndEvil: Several Zi Ri are not only immortal, high-powered sorcerers, but have been around since roughly the beginning of the universe, and may adopt this attitude. The sourcebook comments that this is "probably a bad thing".
* AlienGeometries: Anything involving the god "Here" (Space/Location), his elementals, or enough of the associated magic Art can easily invoke this.
* AlienSky: Compared to the terrestrial sky, certainly: multiple moons that move somewhat erratically, the sun is a rolling crystal orb which ignites at dawn and is extinguished at dusk, stellar objects that wind about and fence each other, or move stars around, and the seven creator gods looking down on the tree. And all of it but the stars are visible during the day.
* AuthorityEqualsAsskicking: While many politicians and bankers and such wield their own sort of power, high-ranking members in many of the guilds that rely on magic are, by definition, potent mages. Especially notable are the Smiths' guilds and the Healers' guild.
* BenevolentArchitecture: The gods filled the world with inhabitable land and other resources for the primes...
* MalevolentArchitecture: ...And put all the livable areas on branches whose edges, up to twenty-five miles away, are filled with custom-designed monsters.
* BadPowersBadPeople: Subverted with Mind magic. There are legitimate reasons for studying that element, not involving MindRape, but anyone who's good at it is automatically suspect. See the entry below on TheDarkArts. Subverted with some monsters as well; some generally benign monsters have rather dire abilities.
* {{BFS}}: The three-handed sword, a popular weapon among Herethroy warriors, who have enough limbs and coordination to actually use one effectively.
* BlessedWithSuck:
** Parents of different prime species can have a child, using complex magic. The hybrid kid gains the intellectual and magical benefits of both races at all times, and must shift between the two...painfully and involuntarily every hour (they can resist, but that hurts more) using the physical benefits of the current species, and dies young of debilitating illness.
*** Theoretically, said parents could use even more magic to ensure the child comes out looking like only one of them. However; that's another ritual spell, and given their preparation times most people probably don't have time for that.
** Nendrai have incredible Change magic talent plus immortality, but are designed to crave gifts from primes, have emotions like love and friendship, have a cruel streak and limited control over their powers, and cry tears of jagged glass. Oh, and they're specifically denied the painless healing of the official Healing element. This all appears to be due to Gnarn, the god responsible for nendrai, carefully crafting them to be a very troublesome monster for the Primes.
*** Except for their lack of access to Healing magic, most of these are not actually canon; the (co-)author's in-character journal has dramatized some things to make for an easier-to-relate-to character. As written in the sourcebook, nendrai are ''terrifying,'' and their lack of healing magic just isn't enough when they can twist magic and space around themselves to make good their escape from a nasty situation. They take what they want from whom they want, prime or otherwise. Fortunately, some of them have enough enlightened self-interest to realize that even they couldn't survive drawing the attention of all the great heroes on a given stretch of the Tree, and are happy to trade their considerable (and free) magic for whatever it is they want but don't have yet.
* BlueAndOrangeMorality: A number of monsters on the tree seem to have very odd senses of right and wrong; the most notable (albeit not really native to the tree) are the locador elementals, creatures of space incarnate. The god they're associated with, "Here", may qualify as well.
* CosmicHorrorStory: "Here," god of Space, appears as a skeletal Herethroy carapace with shifting holes revealing unspeakable things. Elementals of position can be all the more terrifying for not having even ''that'' much personhood in their structure, UncannyValley notwithstanding. Creatures from outside the universe sometimes break in, like a miles-long killer slug.
* CthulhuMythos: Likely inspired the god "Here", if it's not [[AlienGeometries immediately evident]]. He's implied to be related to (or [[AFormYouAreComfortableWith actually be]]) Yog-Sothoth.
** Almost certain, given that it's highly recommended, rather than throwing in offworld horrors, to describe "Here"'s progeny in "crawling Lovecraftian terms" (and then top it all off by calling them "angels" since they do a god's bidding).
* DeathIsCheap: Used, but not quite as cheaply as expected. While certain healing spells can bring back a person after they're technically dead, most of these work best right after death, and leave the patient in quite a bit of anguish for a week or two. Resurrection after the soul has passed on (which doesn't take long) is much more difficult, with mistakes made frequently enough to discourage most attempts.
* FateWorseThanDeath: "Doorwaying", letting a non-prime into a city, gets you ''multiple'' executions. With an equal number of resurrections if it was an angel sent by the gods, or otherwise did no real harm. Healing magic is cheap enough in general that corporal punishment is not seen as a great thing - and getting killed and resurrected is just an extreme form of such punishment.
* ForceField: Via magic using multiple methods. Perhaps the most interesting is literally creating [[AlienGeometries extra space]] between yourself and the incoming attack
* EmpathicWeapon: Weapons and spells can have semi-intelligent spirits. "Bound spells" can be made to go off under particular conditions, though these are far cruder than instilling an item or spell with spirit.
* GodIsEvil: Some of them, some of the time. Even kindly Virid (Creation) made a small percentage of her species into mixed-gender people (A fourth gender; they have three naturally), [[RuleOfDrama and made the rest instinctively or dogmatically hate them]].
** Mileage Varies within the species: if they behave like one of the two genders that combines within them, they're tolerated (if they aren't killed as eggs), if they act like the other, they're hated.
* GodIsInept: Any number of questionable design foibles were put into the world by the gods. The Khtsoyis origin story, the origin of the seasons (in particular, the season of "Surprise"), and so on.
** The gods in concert would be omnipotent, but have never cooperated that much since the world was first made, if then; any of the gods can find the answer to any question it wishes, but they don't always know what questions need to be asked.
* GrowsOnTrees: Played with; while the grand examples are absent, there are plants that grow small amounts of metal or other hard materials in their leaves, nuts, or so forth. In a setting without much metal, this can be invaluable to harvest and refine. Also, due to their {{Magitek}}, Primes can do quite a lot with certain types of nut.
* HitPoints: Though the units are different than those in the game rules, primes have discovered there really are distinct health units that lead to death when depleted, and that practicing having your spirit hang onto an injured body raises your injury tolerance. Adventurers have volunteered for scientific "titration" (''i.e.'', "death by a thousand cuts") to get this practice. These units aren't exactly quantal - that's a gameplay abstraction - but it's still quite measurable how well a spirit can hold onto a damaged body.
* JerkAssGods: It appears the universe was created as a form of entertainment for the gods and their various otherwordly friends. So the constant misfortune heaped upon the Primes is purely because the gods find it amusing to watch them deal with it.
* LivingForeverIsAwesome: Zi Ri expect to live forever, and are built to withstand it mentally. Powerful sorcerers try for this too, but since it requires learning Mind magic, they risk being accused of ImmortalityImmorality.
** This is played up more in some in-character journals than is really stressed in the sourcebook. Mind spells may be hard to acquire, but the ones that only affect you are generally not held as evil in the sourcebook. Unwise, perhaps, but not evil in themselves.
* LostTechnology: Much of society was wiped out during The Holocaust Wars, which means that ancient artifacts are frequently found by adventurers. However, the trope is notably subverted in that magic theory has advanced significantly over time. So while the artifacts may be valuable for their historical significance, their effects tend to be crude and trivial by modern standards. The sourcebook mentions a famous enchanted weapon that would be considered a homework assignment for second year students at most academies. Holocaust War artifacts may be especially potent because nobody would dare make such destructive things anymore, but probably not because they're beyond the reach of modern enchanters to make. On the other hand, the gods ''did'' get more personally involved in the old days; god-touched artifacts are ''much'' less common now (and were never exactly plentiful).
* MadeOfIron: Justified, since there's plentiful healing magic, and survival is more dependent on the ability of a creature's spirit to hold on to its body (see the example on HitPoints) than the survival of any specific part of the body; even if there's an arrow through your heart, if the spirit clings well enough, it can keep beating.
* MagicAIsMagicA: Subverted slightly, due to the gods' direct influence over magic. Primes have ''tried'' to make this true by developing "scientific" types of magic that are predictable... mostly.
* {{Magitek}}: Magic ''is'' the technology. Why use expensive glass to make a crude tool that imitates an off-the-shelf microscopic-vision spell?
** Though there are some reasons to use such things, especially where information-gathering is concerned - information-spells are inherently unreliable. Sometimes you'll know they went wrong. Others, you won't - and that's when they're most likely to be ''horribly'' wrong.
* MagicPoints: Justified as part of the world's physics. Primes get distinct units of "cley" (perceived magically as keys), and spells usually cost one unit, with more contributing more power if the caster is able to shove them in / if a spontaneous spell happens to use them. On the flipside, you can try to cheat, getting a weak spellcast without actually using a cley - but you need (and risk) one cley to make the attempt.
* MindScrew: This one is about what magic can and can't do, particularly healing and destruction. One cannot either heal something so much it can't be destroyed again, nor destroy it so much it can't be brought back. Granted, the complexity of the reversal gets higher with each heal/destroy cycle.
* MundaneUtility: Most primes know spells with little adventuring use, for tasks like creating water or cleaning dishes. An in-book example shows an ordinary woman fretting over whether to study an obscure magic art to learn a better dish-washing spell, versus getting (expensive) clay dishes which the more common spell won't destroy like it would wooden ones.
* NeglectfulPrecursors: Some of the gods qualify, and the magic tied to their Art shows the repercussions:
** Pararenenzu's absent-mindedness explains the innate 5% failure rate on Knowledge spells.
** Kaimiri, God of Time, has been sleeping since the world's creation, but left his servants with very detailed instructions for every occasion; time gods can do that.
** Merklundum Harnipsum The Dog Who Killed A Fish (Water)'s only known miracle is to show up and scold a scholar who abbreviated zir full name, and that only happened once. And even ''that'' may be apocryphal. Zie is similarly resting, and advanced water magic (the sort which usually gets a god's direct, if brief, attention) tends to be underwhelming for this reason.
* NoOntologicalInertia: Magically-created objects soon vanish by default, but it's fairly easy to make them permanent. The book points out that the existence of Healing magic implies that everything has a natural "intact" state, and low-level Healing spells make wounds vanish only temporarily.
* OurGodsAreDifferent: The gods, referred to collectively as the seven-plus-twelve are divided into two categories:
** the seven verb gods, known as the creator gods, which each had a hand in the creation of the world itself and a prime species (or two), and each manage a magical Art related to how a things are affected; a Verb. Among them are creation, destruction, knowing, changing, sustaining, healing, and controlling. They generally sit in the sky and watch, rarely intervening in mortal affairs; two of them are known to visit on a frequent basis, but say and do nothing of consequence.
** the twelve noun gods, who live on the tree itself and manage an element, a magical Noun. These gods are much more active in the affairs of mortals. The twelve nouns are fire, water, air, stone/metal, plant matter, animal matter, time, space, mind, spirit, sensation, and magic itself.
* PowersAsPrograms: "Pattern Magic" acts like this, but it's only one of several known methods of working with the inherently unpredictable force of magic.
* PowerPerversionPotential: Mind and Body magic. Reversed with cley transfer, which grants someone more MagicPoints but requires an embarrassing hug-and-kiss ritual.
* RageAgainstTheHeavens: A Zi Ri is known to have once blasted the Goddess of Creation with the spell "Grand Inferno", [[spoiler:with no effect]].
* PersonalityPowers: Justified, since the same gods designed the primes to their liking and gave them a knack for particular magic elements.
* ScrewDestiny: The cyarr (hyena-taur) race of non-primes believes it can achieve prime status and become one of the gods' favorite races, if only they exterminate one of the existing prime species.
* ShapeShifting: Orren naturally shift between anthropomorphic and small, feral otter forms, and can adjust transformation spells cast on them. The spell "Cloak Of Another God" turns one prime temporarily into another and is moderately easy.
* TheDarkArts: Mind magic is treated as this in the eyes of Prime civilization. This is due to the generally intrusive or controlling applications it's put to; there are legitimate uses, but even then it's considered suspicious, and "mind mage" has the same ring as "necromancer" in other settings. The negative reputation is played up more in some in-character journals than in the sourcebook; in the book, merely being good at mind-magic generally won't get you shunned, so long as you don't use it (in however benign a manner) on anyone but yourself. Given that Birkozon's stated ambition is total, if indirect, control over the Tree, anyone who meddles in mind-magic (Birkozon's domain) may be thought some degree of stupid, but so long as you keep it to yourself, everyday people have better things to worry about than your personal damnation. (Though there ''are'' those - in the Healers' Guild and knightly orders - who are more vehement about it.)
** Necromancy does exist on the World Tree, but is at most viewed as "Rude" rather than "Evil" by those not related to the animated. Family? They might sue you...or worse. Compounded by a spell that creates a dead copy of a subject.
* {{Uncoffee}}: Kathia, a spicy drink made from the leaves of the kathia plant, is described as similar to coffee or spiced tea. There is an associated character flaw, "Needs Kathia to Wake Up".
* UselessUsefulSpell: There's a listing for the spell "Destroy the World," along with other mighty spells likely way above anyone's skill level.
* UsefulUselessSpell: Sythyry regularly casts "The Raven's Beak," which does practically nothing, but gives experience in every magical element.
* VillainBall: Used with some of the gods. We're told that Gnarn (Change) would have been Goddess of Destruction, but let her "brother" Accanax have the job.
* WeatherDissonance: Built right in; a one-month-long season known as [[ExactlyWhatItSaysOnTheTin Surprise]] involves all nature of interesting and odd weather, in addition to typically being very hot or very cold for the entire month. The rest of the time the air elementals in charge of weather behave... more or less, and getting a universe like the World Tree to have mostly temperate, liveable weather means those elementals are doing a great deal of work indeed.
* WhatMeasureIsANonhuman: Non-primes variously know, don't care, or ignore that the gods don't particularly care about them, and the terms "monster" and "non-prime" are used nearly interchangeably; the former is less polite. Primes' "mageriums" (mind-spirit connection and link to the gods) are visibly different too.
* WorldTree: Explicitly, with literal branches and leaves and amber.
* YinYangBomb: An interesting example, the spell The Infinite Grenade uses a combination of destructive, healing, and sustaining magics to repeatedly detonate the titular grenade.