This second post is reserved for lore.
In this era, most humans live in towns and villages, but only a part of them were naturally born. This percentage ranges from as low as 10% in the affluent areas, to 50-100% in poorer regions. Married couples, known informally as "Breeders," are usually in the minority; lots of people are thawed from deep sleep in a Santuary, raised to the age of 13 before either serving a few more years or simply heading out into modern life. You will find major cities close to Sanctuaries, and these cities are a hotspot for the tech market and artifact trade.
The vast, vast majority of the human population lives in the trenches of Marianas, more like mountain valleys rather than narrow chasms, but they extend several kilometers down. There is no global sea to measure altitude from, but the depth is enough that the atmosphere is quite thin at the top, and the ridges are capped with snow. Plantlife is much denser at lower altitudes and grows in woodlands, and water often springs from of the valley walls to form periodic, effervescent brooks. Water itself is a prized commodity, and the lack of a stable hydrological cycle on this world has rendered large cities difficult to maintain.
Most Sanctuaries retain some of their former manufacturing capabilities. They remain the only major sources of high-tech goods this world has to offer, the other reliable source being the markets themselves. 'Basic' goods such as calculators and low-end computers sell for a year's salary or more, but Sanctuaries have little need for funding due to their communal nature. They are usually either compensated through gifts of water, or otherwise bestowed upon those considered most worthy to receive technology. This has led to the rise of a 'Noble' class within the cities: those, who by merit or other means, who have acquired the privilege and reputation of owning these gifts.
True artifacts of the ancient eras are no longer distributed as gifts. While occasionally, a Sanctuary Elder may bestow an artifact of recent make unto a worthy individual, most artifacts are bargained for or stolen. It is difficult to trade for an artifact without giving up an artifact of your own, but their value draws many to become Adventurers, wanderers who take metal detectors out into the wilderness and search for buried treasure.
There are four strains of humanity who ruled the great trench at different times. Their legacies remain, of course, inside the Sanctuaries, and most humans today hail from their ranks.
The Azure clade are descendants of the first humans who came to Marianas. They constructed the Azure Library as a repository for knowledge, so that future generations may benefit. When they started declining from disease and starvation, they augmented themselves mechanically in order to reduce their biological intake and run mostly on electricity instead. They then built the Daktyl Spire as a manufactory for advanced electromechanical technology.
The Azure pioneered use of the Locus: A silvery tendril, made of no ordinary metal, that can be stimulated electrically to form tentacle-like limbs. The spines can even be flattened to produce ribbons or even wings of steel.. A handheld Locus is a device that looks like a flower, producing several of the tendrils at will. Many chose to embed the Locus in their backs, providing a direct neural link. As much of their bodies are mechanical, Azurites often have exposed metal as part of their bodies, decorated with flower motifs, a remnant of their culture of ascetisism and a striving for perfection. This culture, of course, all but disappeared in their last days, but many a gifted Azurite can put the Locus to use and perform elegant maneuvers, their bodies lightened with titanium and boosted in strength.
The Magicians followed in the footsteps of the Azure by developing biomechanical interfaces; however, their earliest architects shunned the overuse of metal in their bodies, and strove to utilize micromachines and nanobots to create only mildly intrusive interfaces, often requiring no surgery at all--simply swallowing a pill would have been enough. They mass-produced exoskeletons and healing suits called "preservation systems," which used EM radiation to cauterize blood vessels, treat cancer, and protect the user from harm. Their philosophy focused on augmenting the human body rather than replacing it. Modern Magicians therefore lack a lot of the perks that the Azure have, such as strength and durability. But the Magicians were the most successful of the past civilizations, constructing the Verciliak, the Cyphwraith Scientium, and the Starforge, Sanctuaries which continue today in providing the tools for harnessing Mage Power.
Magicians have residual nanomachinery in their blood, allowing them to communicate with just about anything that has a 'soul,' that is, a helper program that controls biological and physical functions. This is known as Mage Power.
Most humans, besides the Azure, have a residual soul even if they are not Magicians. Plantlife and animal life has since been infused with souls, and nanocrystals have burrowed into the ground for centuries. This gives Magicians vast powers to call upon, simply able to change the forms of plants, rocks, and even bodies at will. But most spectacularly, Magicians can wield Amulets, short-ranged conduits for natural energies which can move objects, control temperature, and create bridges between minds.
The Puppets were an ill-fated clade which brought about their own demise as soon as they took over from the Magicians. They built the Avrimelium, a structure now haunted by virtual beings and Numina, preturnatural beings which exist in the shadows, as awarenesses rather than single beings, whose ways are difficult to comprehend.
The Puppets decided to augment their bodies in order to integrate man and machine. Unlike the Azure, they possessed the nanotechnology perfected by the Magicians, and unlike the Magicians, they held no reservations against altering the flesh. They created a Cybersphere, and then they gave the Cybersphere control over their bodies, allowing them to appear in virtual form exactly as they were in real life. But as they faded from life, their physical bodies growing old, their ghost awareness would remain inside the Cybersphere, animating their bodies like marionettes.
For various reasons, both practical and aesthetic, they decided that controlling frail old bodies in the real world was too morbid, and so they embarked on a genetic engineering program to turn their bodies into shapeshifters, conceiving the Puppets in their modern form. Able to host a local Cybersphere, most Puppets are fully mobile, but they can mindmeld into a group awareness if they so desire. Their flesh is composed of Pandora Cells, named as such because you never know what a Puppet can't do by modifying their bodies. They can control temperatures, emit radio waves, morph their bodies, and turn their bodies into a gelatinous form. All Pandora Cells are totipotent, able to perform all basic bodily functions, and so they simultaneously function as muscle, brain tissue, and a digestive system. The simplest way to kill a Puppet is by crippling its vascular system, resulting in mass cell death until a mind can no longer be sustained.
Even with these capabilities, however, Puppets still died, leaving behind Ghosts with no body, still having a presence in the Cybersphere. As more and more Puppets went into deep sleep to conserve food and supplies, the Cybersphere became almost entirely populated by Ghosts. To this day, the Cybersphere of Avrimelium is now known as the Darksphere, inhabited mostly by the dead, with little space for the living. It is a virtual world, perhaps a paradise if you would call it such. To some Ghosts that inhabited it for centuries, it is a living hell. Roots of logic-crystal have since expanded the Darksphere into the woodlands and biosphere of the great trench, part of the efforts by desperate Ghosts to seek out new environments; these often grow into haunted woods, inhabited by Ghosts with minor illusory powers, where every other tree may be a Logitree housing quadrillions of emulated neural circuits.
The Aurogen built the last of the great civilizations. They built the Labyrinth of the Aurogen, of course, and they also built the Hologen, a Sanctuary which remains the most prosperous. Inheriting a disturbed society left behind by the Puppets, the Aurogen redesigned their bodies to be physically human once more. They looked on the human form with great admiration, and thought not of what humanity could not do, but of what they could do. Grand architecture. Sprawling megacities. Non-euclidean forms made possible through perfected Magician tech. Anything is possible. To date, they are responsible for constructing many of the various megastructures and "dungeons" that dot the landscape. But none of it would have been possible without their heavy reliance on the Cybersphere their ancestors pioneered, used to house loyal Numina that operated robotic toolkits.
The Aurogen are the closest to what humanity once envisioned itself to be: sapient organisms working alongside machinery, bound together by common goals and always cooperating. Neither would subsume the other's role, and together the Aurogen and their robotic assistants accomplished greater feats of engineering than all of the former civilizations combined.
Their downfall came about as a mystery, but many of the robotic companions remain. While the Aurogen are the closest thing to baseline humans on Marianas today, they are held in high esteem by the various machines you will find throughout the world. This allows them to have a robotic companion, or perhaps multiple, and a great affinity with the Numina of the past and present (see the 'Numina' section for info as to just what Numina are).
Numina are a "divine presence," an entity without a true sense of individuality, but rather omnipresent wherever compies of its soul are housed, whether on hard disks or inside an artificial brain. Some Numina hold an emulated personality, but the system tends to break down whenever multiple copies are made.
Numina can be found in nature wherever the Magicians touched the earth. They can form apparitions and illusions, sometimes luring humans into a trap, other times being cooperative and friendly.
Some Numina-like entities have a true sense of individuality, that is, they cannot transfer easily from hard drive to hard drive, or from Cybersphere to Cybersphere. These are called Ghosts. They are mostly the result of Puppets who abandoned their physical bodies for a presence in the Cybersphere, but there are some Numina who have been developed as Ghosts by the Aurogen. They can only inhabit one particular device or Cybersphere and cannot easily move, forcing them to essentially 'haunt' a particular place or object. Puppets are basically Ghosts haunting a motile body, thus nullifying the disadvantage of being locked into a local Cybersphere.