So I had a dream and it had a plot and a setting and stuff and the setting was called Galatea in my brain and I don't know why but I needed to write it down. So I am. Writing it down.
Magic
A fair number of people - about 1% of them - are born with some kind of magic. It's not obvious then, however, as magic can remain inert for a while. The first time someone with magic performs it is called Expression. Expressing magic is always a strictly voluntary process - you won't one day suddenly wake up to enchanted teddy bears - and the way to do it is somewhat ineffable. It's technically possible for someone to Express magic at any point in their life, as it only depends on them having magic in the first place and finding the correct subjective trigger to do it, but normally by the time you're an adult you have tried doing magic for long enough that you probably don't really have it (although late-in-life Expressions are not unheard of).
There are four types of magic you can have. They are mutually exclusive, and you'll only find out which kind you have when you succeed at Expressing your magic.
Enchantment
Enchanters' thing is imbuing objects with magic. They can create magical artefacts by spending a while thinking about all the effects they want and how they'll related to/be used with the object, and then dumping that effect into it. Possible effects range from making a sword really really sharp to creating a golem to even more complex things. One cannot add magic to an already magical artefact nor replace the magic on it without thoroughly destroying it (and magical artefacts are by default more resilient than their nonmagical counterparts), so it's impossible to upgrade an already existing artefact. It's not necessary to keep all the details in working memory (à la Hex) to enchant an artefact, you can just write it all down and consult as you enchant. You cannot however pause enchanting, even to go to the loo, nor get distracted from it; if you do, the artefact will only have whatever magic you managed to pour into it up to that point.
It's possible to enchant separate pieces of a thing which can communicate with other enchanted things (and build a computer that way). It's not possible to create artefacts that enhance their user's capabilities - no eidetic memory necklace. Only the artefacts themselves are magical, and they cannot easily simulate any of the other kinds of magic. Enchanters have a sort of mana charge that they spend in order to turn an object into an artefact, and they have intuitive knowledge about whether they have enough mana to create a given artefact they have in mind. They don't have a maximum amount of mana, it merely keeps accumulating inside them from the moment they're born at a constant rate.
When an enchanter attempts to Express magic, they will typically accidentally make a magical artefact out of a random object nearby. Given the amount of mana they've accumulated since birth, it'll frequently be a very powerful artefact, with very bizarre/useless/dangerous powers. Because of this, when trying to Express magic, people usually surround themselves with harmless items and/or items they would like to see turned into artefacts.
Elaboration on artefacts
Arcanism
Arcanists' thing is imbuing symbols with magic. They're the stereotypical wizards, with magic scrolls and spells, casting fireballs and what-have-you. Each arcanist's spell is unique to them, and created by them. An arcanist has to pick a string of "symbols" - and they do not have to be written, a sequence of words spoken out loud while striking a pose is as good a string of symbols as any - and assign a magical effect to it. Thenceforth, for the rest of their life, whenever they invoke that string of symbols, that effect will happen. Furthermore, if the string of symbols happens to be written, they can write scrolls with them that other people can use to cast, a process which then destroys that scroll. Arcanists also have mana that recharges indefinitely, and when they create a spell they get an intuitive reading of how much of their mana casting that spell costs. Creating a scroll also spends that much mana.
The types of effects arcanist magic can have are effects on other things/people. They can heat up the environment, create fire balls, perform telekinesis, lock or unlock doors, etc. Other than magic scrolls, none of an arcanist's spells has a permanent effect, they're all instantaneous/sustained. There's an upper limit to how powerful/destructive a spell can be. Spells cost more mana the shorter their strings are, and the less their strings have to do with their effect.
When an arcanist attempts to Express magic, they will usually accidentally tie some random specific symbol to a random magical effect. Since it is easier to associate spells with symbols that are already related to them (a fire spell that doesn't contain any references to the concept of fire will typically cost much more mana to cast), people usually start spewing many obscure nouns when trying to Express magic so they won't accidentally bind themselves to conjuring newts whenever they say "hi."
It is now common to use a conlang specifically created for this, that won't be used in regular conversation, especially for shorter/more expensive spells. When time is not of the essence, though, it is typical to go flashy and include gestures and poses and what-have-you.
Elaboration on spells
Elementalism
Elementalists' thing is imbuing themselves with magic. At any time, an elementalist can grant themself a blessing, replacing the previous blessing they had. They are called elementalists because some very common blessings in the past were AtLA-style elemental bending, but other blessings include flight, strength, speed, endurance, and cognition. Each blessing has its own mana charge, which recharges whenever you're not actively using the blessing but have it on - in other words, if you pick flight as your blessing, you can fly until you run out of mana, and then you have to recharge by not picking any other blessing and not flying (so elementalists always have at least one blessing active). Elementalists have the most direct intuitive access to their mana charges, knowing pretty precisely how much more they can use a given type of magic before they run out of mana. Also, unlike the previous two magic forms, each blessing has a mana cap, and doesn't recharge indefinitely. An elementalist can swap blessings instantly if they're not actively using a blessing, and not at all if they are.
When an elementalist attempts to Express magic, they try to pick a blessing, with no control over what it will turn out to be. Relatively speaking, elementalists have the least chance of a negative consequence upon Expression, since they can stop doing whatever magic they got as soon as they get it, and they have a pretty intuitive understanding of it. Consequently, there aren't any typical precautions taken by people attempting to Express for the case they turn out to be elementalists.
Elaboration on blessings
Metamancy
The three other types of mages make up about 99% of all people with magic. The remaining people are metamancers. They don't have mana, nor can they natively perform or generate any types of magic on their own. Metamancers, rather, can manipulate other people's magic. The thing I said about how it's impossible to disenchant/upgrade an artefact, or how an arcanist's symbol is forever tied to a spell for that arcanist, or how an elementalist can only recharge a blessing's mana charge while it's on? Yeah, metamancers can fuck with all of that. And in the very distant past, they used to! They used to be magic teachers and scholars, and many of the artefacts and spells of the past are actually way more powerful/versatile than modern ones because of metamancers improving them.
But metamancy is the least intuitive of all forms of magic. Or, rather, the way magic is used is very personal and subjective, and a metamancy has to be able to figure that out for each person/effect they're helping/studying, to understand how to mess with their magic.
Or the metamancer can just downright steal someone else's magic.
Not permanently, but a metamancer can, say, drain an arcanist of their mana and use their spells and even create new spells and scrolls. A metamancer can get an enchanter's magic and create their own artefacts. A metamancer can nonconsensually "borrow" an elementalist's blessings, causing them to be inaccessible for as long as they have it (though they can't recharge another elementalist's blessing's mana like that, naively). And a subtle, smart metamancer can just pretend to be one of the other types of mage by sneakily draining some magic from people around them. If a metamancer's actually appropriating and using someone else's magic, it becomes as easy for them as it is for the person they stole magic from. A metamancer can also disenchant an artefact and absorb enchanting mana from it, or destroy a scroll and absorb arcanist mana from it, or capture excess mana escaping an elementalist's use.
There are no externally discernible effects to a metamancer's Expression. The metamancer themself merely gains a new sense, which can be used to perceive magic. Metamancers can tell whether someone else is an enchanter, arcanist, or elementalist, even before they've Expressed, but it's impossible to detect whether someone is a metamancer - if a metamancer is using elementalist magic, they will read as an elementalist to other metamancers; if they don't have any magic - active or passive - they will read as a nonmage. Non-metamancers cannot tell between mage types or mages and nonmages without seeing actual magic in action.
A very little-known fact is that metamancers can actually turn other people into mages. The knowledge of how to do this has been lost, however, and it is suspected that this requires the sacrifice of someone who is already a natural mage.
Elaboration on metamancy
Aesthetics
The aesthetic of the setting is magitek fantasy. You have stuff like stone vehicles à la Disney's Atlantis, balloons, magical fire-arms, automata, computer-like things (with different aesthetics, like crystal balls), while at the same time having various kingdoms and people with swords and lost artefacts and power mad evil mages. Mages (with the exception of metamancers) are high status, and there are different functions that they tend to occupy. There are various university-like institutions where magic can be taught - principally arcanism and enchanting, elementalism is easy enough and metamancy is... well - and your kid having magic is an almost guaranteed ticket to a cushier life and higher social status.
History
Most of the history of the setting is similar to early human history on Earth, modulo magic. At a time roughly analogous to 1,000BC, though, a great conqueror appeared. He was a metamancer, and had a guild of same with him, as well as an army with many magical commanders. That guild had spent decades performing rather horrifying experiments with various other kinds of mages, and continued performing same as the war progressed. Half a continent had been unified under that banner before other countries banded together and fought back, performing some of those experiments themselves in order to be able to compete.
The conqueror was eventually defeated, and all metamancers working for him were executed, and the remaining kingdoms on that continent divided the territory and decreed laws that prohibited the practice of metamancy. Works of metamancers were burned, artefacts were lost, society was set back a few hundred years, technologically. A great taboo was brought to existence, which was only reinforced by a few powerful metamancers who tried to overthrow these governments and were painted as evil and mad. It is now very rare for people to openly perform metamancy, and occasional witchhunts happen.
Elaboration
Religion
There are a few religions, but the most popular one by far is a polytheistic one with four major deities: Laoku, Teinn, Bezana, and Vinkar. Each of these is associated with one type of magic plus a myriad other subdomains.
- Laoku the Enchanter is the god of work, creation, ingenuity, and beauty. He is said to have fashioned the physical world and, when Bezana created life and humanity and Teinn elevated them from other animals, he gave them magic. He is typically depicted as a smith, with a hammer in one hand and a chain in the other;
- Teinn the Arcanist is the goddess of knowledge, justice, writing, and war. She is said to have taught humanity how to write and communicate, thus elevating them from mere animals. She sits in judgment of the souls of the dead, sending those deemed unworthy to another life so they can learn their lessons. She is depicted as a scholar, always reading a book and holding a lantern;
- Bezana the Elementalist is the goddess of ambition, growth, harvest, and healing. She created all life on the planet, and she's the one who taught humans that there is more to the world than meets the eye, and they should go figure it out. She's depicted as a sort of nymph, often with animals around her;
- Vinkar the Metamancer is the god of manipulation, cunning, corruption, and disease. He opposes the other three, destroying what they create and corrupting what he can't destroy, tempting people into damnation. He's depicted as a young man made of shadows, always at night.
Politics
The five kingdoms on that continent after the war eventually became three very strongly allied ones - one could even consider them a single very large kingdom. Each of the three is associated with one of the three main magics and deities, and their regents have religious as well as political positions. The royal families are said to have been chosen by the gods themselves, and this blessing means that the regents are always mages. This is, of course, quite false, so they've developed various, variously elaborate ways of faking it when it turns out not to be the case - 99% of the time (actually a bit less because they're incentivised to have many children due to this and there isn't a strong primogeniture custom). Being good at magic is a good way to rise in social and political status. Famous or powerful mages often get marriage offers from nobles, in the erroneous belief - or perhaps desperate hope - that they are more likely to produce magical offspring.
The Three Kingdoms
World Map
Languages
Political Organisation
Guilds
Dates and Customs
Some more details starting here
