The Paper Mache Dream

"We only experience reality to the extent that is necessary for our own survival."
Humanity destroyed the planet in nuclear holocaust long ago. Afterwords the world was so irradiated that sensitive tissues used in traditional sensory organs could not survive for long, furthermore ionized particles and stray photon energy made things like vision and electroception impossible. So new organisms with new body types and new senses were forced to evolve.
In this new mad world evolution favored a form of abstract psychic warfare over clarity of perception and lucidity. Inconceivable beasts rose up in the wake of humanity forming their own societies and hierarchies in the process.
Now in a world of psychedelic nightmares and mind altering magic sanity is viewed as a curse
As a result of the convergent psychic evolution experienced following the destruction of Earth, with all beings having been linked together through a globe-spanning psychic network, they persist now in an emergent reality that coalesces from the shared experiences of all beings.
This emergent internal reality that overrides the perception of all organisms is referred to as "The Paper Mache Dream."
The ability to alter the dream by altering the mind of oneself and others is the very nature of the psychic warfare in Polygondwanaland. The perception of fire within the dream melts flesh as well as any actual fire can (and sometimes better). A castle built of the mind posseses as much physicality as one built of stone. Those who are not within the dream however cannot experience those within it, and cannot be experienced by them either.
One such forbidden lethal technique is to restore a being's lucidity, ripping it from the dream and into the horrors of the real world which given the state of things, quickly breaks down the mind of any psychonaut unaccustomed to life outside the vale.

Geography

The Dream is a chaotic and shifting web of the mindscape. Comprised of the psyche of every inhabitant thereof (and some who aren't) a handful of stable areas have manifested out of different forms of shared madness amongst the masses, each one more insane than the last.

• The Madlands
A comparatively peaceful place to live in Polygondwanaland. The Madlands are on the outskirts of the Paper Dream far to the west. Ruled over by the Lizard Wizard, most wise of the Etheric Elders.

While afflicted by the madness that grips the Paper Dream, denizens of the Madlands more often than not lead functional lives and try to achieve a sense of what might closely resemble normalcy (if not a mockery of it.)

• Mercuria Grove
The Grove is somewhat less stable. The people of Mercuria are prone to wild and suddenly changing whims. They take great pride in the high-arts and flights of fancy one moment and then seek to cut down those around them the next.

As such while you'll find very few cities in Mercuria, the forests are brimming with lavish estates and high culture, though if their inhabitants remain intact they do so in a terrifying hyper-extended state as this region has never experienced proper stability.

• Psychopia Ruins
The ruins of Psychopia are reknowned throughout the world for their impossible grandeur. Once known by the name "The Kingdom of Mania," it was filled with the greatest & most powerful minds Polygondwanaland had ever known. They erected countless superstructures to perform their studies and experiments within.

However the kingdom fell into ruin when the Resident Wizard attempted to empower the minds of the kingdom's residents even further, pushing them beyond a boundless stream of supersonic thought into a blind chaotic tunnel of noise that induces a boundless fury within those who enter Psychopia. This is however to the shaping of the whims of an Etheric Wizard and as such is ultimately what is best for those who choose to reside here.

• The Catatonic Void
As above so below, as without so within. It both insulates and inflates this world, the Catatonic Void is on all sides of Polygondwanaland as well as at its very core.

The visceral brutality of the real world and the psychic chaos of the dream can be too much at first for those born on Polygondwanaland and so the Void exists to contain the suffering of existence by sublimating them into a new mode of being.

At its core all of Polygondwanaland is made from Void and the psychic energies of those healing within it. All within the Void are one with each-other and one with it, one with the Dream and one with Polygondwanaland

It's said if one were to wander into the void they would quickly lose themself within the Dream for 1000 years before being reborn anew. However a sufficiently powerful Psychonaut might be able to keep their sense of self in this place, at least for a few minutes.

History

Humanity destroyed the planet in nuclear holocaust long ago. Afterwords the world was so irradiated that sensitive tissues used in traditional sensory organs could not survive for long, furthermore ionized particles and stray photon energy made things like vision and electroception impossible. So new organisms with new body types and new senses were forced to evolve.
This resulted in a new sense evolving in the absence of perception; first they gained to the ability to sense one another, then they gained the ability to feel one another, and finally they gained to ability to feel AS one another. Until the barrier between all minds and organisms was removed. Denizens of Polygondwanaland are referred to as Psychonauts.
When a Psychonaut is born into this world, they are (if they're lucky) quickly driven mad by the overwhelming global psychic interference allowing them to be pulled into the dream. From here they don't exist anymore, not yet, upon succumbing to the global psychic network their individuality is lost.
However as they age, if a Psychonaut can slowly remember they exist, then they will remanifest into the world at long last. Those who never manifest become a part of the psychic background radiation... or worse.