The World
The world is this cool fantasy landscape with lots of huge floating islands where most of humanity lives. There are continents and oceans but they are very dangerous because of the rains of acid (whose clouds don't quite reach the floating islands and are diluted there) and the horrible twisted monsters that roam the land.
Shapes and Shifting
Everyone is born with a few "natural shapes." They age synchronously in all of them until a certain condition to be explained is met, and how they are selected will be explained, too. There are a finite number of "types" of shapes people can have, sometimes related to elements (air shape, water shape, etc), sometimes other things. These shapes are always humanoid or humanoid+ (like humanoid + wings or humanoid + gills + fins). Shifting to one of your shapes is kinda terrible and gross: you basically have to molt your current shape, growing the new one under your skin, and it's a process that lasts only about a minute and by the end you shed your old "skin" and have your chosen shape. It's also excruciatingly painful.
In addition to the natural shapes you're born with, you can acquire new ones via a horribly painful process which you can go through by visiting pools of an ooze-like “acid”. When you do that, you gain an entirely new shape type that is determined by the type of pool where you got it; that is, there is a Pool for Ventari shapes, a Pool for Voragera shapes, etc. They're not really acid, but rather as painful as acid, and when you get into one of them they gruesomely reform your body into its new shape. They're indistinguishable from regular water except by an off-coloration and the liquid’s consistency, so any ol’ pool could be one of these, although many of them are already mapped. Most pools are downside, but there are a couple on the islands (not all islands), too, and those’re all for Ventari shapes.
You need to spend approximately twelve hours in a Pool for every shape you already have. While you do, you don’t need to breathe, eat, or do any biological things, but being submersed up to the neck is enough. If you leave the Pool before a third of the process is complete, the form you entered the pool in will be painful and half-melted while you’re in it until you come back to complete the process; if you leave it between one-third and two-thirds, you might become a twisted aberration or just die; after that, the transformation will continue on its own but take longer. The pain isn’t twivamp level but it’s enough that a large number of people do prefer to leave before the first third of their transformation is over and just sacrifice that shape forever rather than return to it and complete the transformation. (Think hex wishcoin level.)
The aforementioned rains of acid then aren't actually acid, but rather water from these Pools all mixed up. Being hit by rainwater basically makes you be affected by several Pools at the same time and they all try to alter your biology and this almost invariably kills you, but sometimes it doesn't. When it doesn't, you become a twisted thing, with asymmetrical limbs and trouble moving, and you lose your mind between the various different ways your brain could be. The monsters roaming the land are these kinds of people, and because of the nature of the transformations they never age, so there are some monsters that have been around for hundreds of years in this torment. It is possible to cure one of these people by dunking them into each of the Pools that are majorly affecting them so that they can complete each of the transformations they got partway through. These rains also happen on the islands, but since they’re far above they’re mostly diluted and mostly consist in Ventari Pool water, it’s not typically that bad.
Each shape you get has a "standard age" which is the (real, not biological) age you are when you first acquire it, and while you're in that shape you age normally, but if you shift to a different shape and then back you'll snap back to that shape's standard age. So, for example, if you acquire an Aestes shape when you're fifteen, whenever you shift back to it from a different shape you'll be biologically fifteen again. The exceptions are your natural shapes: those don't have a standard age until you acquire your first extra shape, and then the age when you do that becomes their standard age. So, someone who is born with a Ventari shape and an Aestes shape and then acquires a Petram shape when they're 18 will have that their standard age for Ventari, Aestes, and Petram shapes will be 18. If they then get a Bronto shape when they're 25, then the Bronto shape's standard age will be 25.
Shapes function approximately the same way as Elcenian dragons’ forms do in that if one dies, you shift into another one, and you can't obtain that shape again. If you die in all your shapes you die for real. Furthermore, if you die in one of your natural shapes before you obtain your first extra shape then the age at which that happens becomes your remaining shapes’ standard age.
The way your natural shapes are chosen is that you get all the shapes both of your parents currently share, plus a shape one of them has that the other parent doesn’t have. All of a person's natural shapes are typically the same biological sex, but very rarely some people have one or more of their shapes be a different sex than the others.
A consequence of the standard aging thing is that past a certain age it becomes effectively impossible to acquire new shapes, since any new shapes you acquire would be old enough to automatically die. Most people wait until a specific desirable age (typically 18, but some people choose anywhere between 20-40) and then start acquiring new shapes.
Whenever you shift, your shape becomes a little bit closer to a “subconscious ideal” to that form. This can be used, for instance, for transition, over several shifts which can make you closer and closer to your desired biological sex.
The list of known types of shapes are:
- Ventari - winged and with great hearing, can deal with rather extreme temperature and pressure variations. Other typical cosmetic alterations include claws, feathers, and a general white motif;
- Voragera - with gills, scales, and fins, the ability to breathe underwater, and sturdy bones and organs that can withstand pressures from the depths;
- Petram - quite physically resistant and dense, have small plates around their bodies and bull-like or ram-like horns, made of stone-like material. Other typical cosmetic alterations are claws and hooves, usually dark-gray, but also rarely gem-like motifs;
- Aestes - run way hotter than a regular human and are fireproof, can breathe fire, often have small horns and a tail, sometimes but not always red leathery skin and/or red eyes;
- Umbra - often with dark-blue or gray skin, dark sclera, have overall sharper senses and an uncanny ability to hide;
- Adamet - nails, iris and hair all have the same metallic color and higher physical resistance (though not as good as Petrams). “Scars” leave behind metallic scales that are quite resistant;
- Bronto - Blue or purple skin, rarely gray, with white hair. Can generate electric charges at touch range;
- Hibera - White, shades of gray, sometimes light-blue, elongated canines, bright-blue eyes, and often have thick patches of hair around their bodies. Coldproof and have a freezing breath.
- Lumina - monochromatic, but can display any color. Glowing iris, they have lines and patterns on their skin that glow faintly by default, but which can they turn off or make glow more brightly;
- Lucivam - green skin, leaf-like hair, pale leafy veins running along their skin, sometimes there’s bark covering them. They can do photosynthesis;
- Tutama - gray and pale coloring, symmetrical features, sometimes exoskeleton-plaques, generally resistant to various kinds of powers the other shapes have.
Magic
There is a process through which a person can permanently sacrifice one shape to give another shape a magical power. In order to sacrifice a shape and gain a magical power, you need to kill it. However, you need to do so in such a way that, right before the shape actually dies, you trigger a shift into the target shape. Then the sacrificed shape will die, and the one you shift into will receive the power.
The specific power depends on the combination of shapes, and it’s not exactly deterministic, but the “flavour” of the power is: each shape has a certain “theme” to it, and the power combines both themes. The themes are somewhat vague, however, and there isn’t complete agreement on what they actually are. For example, powers that involve the air shape often involve movement of some kind, but sometimes involve “lightness.” An example power would be Ventari + Umbra = the ability to sense changes in air currents. It doesn’t always make sense to other people that a given combination should yield a certain power, but it does always make sense to the actual owner of the power - for example, someone might get lie detection from Aestes + Umbra and reason that this is because fire is an element about revelation and light and shadow has to do with abstract concepts. In fact, sometimes it starts making sense only after you obtain a power, such that you wouldn’t have agreed with a description before but then you do.
Since sacrificing a shape kills it, doing this sets the standard age for the natural shapes if they haven't been set yet, and since acquiring new shapes requires a trek through the terrible wilderness of downside, most people never do, opting to wait until they're old enough and have had children then sacrificing one shape and keeping at least two forever, shifting between them to keep from dying of old age.
When you sacrifice a shape into another, the shape you keep has its appearance slightly changed. For example, sacrificing an Aestes shape for a Ventari shape can make some details like feathers or bits of skin red, change eye colour, etc.
Society
The islands are, by and large, isolated political units. There are various different forms of government, and transit between them is possible but not always strictly easy, and often requires a visa and an immigration process.
Technological level is steampunk-ish. Hot air balloons are a thing, zeppelins are not (yet). Given the way people vary in shapes, there isn’t really a world standard way people look, but there are often fashions and/or ways people from certain islands look. Islands with Pools typically have a large population of people with air shapes who move this way and that on wings, and the cities are more vertical for this reason.
There are various religions and variations, but people basically treat each different shape as the representation/gift of a god. The air god is a fairly major one, seeing as it’s the one that has pools on the floating islands, as is the water god as its main antagonist, due to the rains of “acid”. Various denominations treat the other shapes/gods in different ways, some with indifference, some with veneration, some with fear or hate (for they are downsider gods from the hellworld with the monsters).
