Hey folks! I've been using this setting for a few months already in an ongoing campaign, but I really like how it's developed, so I'm gonna share it with you guys.
We'll start with an essential history lesson, and then talk about the current elements of the setting.
Some Nonsense That Happened A While Ago
In that time before time, that space before space, the nothingness that set the conditions for the Big Bang, there was the Plug.
The Plug was a place without mass, without space, without time. There was no void, no God, no events to trigger other events.
There were just rules. Rules, or better yet, code. The underlying code of nothingness, the computational potential to program everything that could ever be.
The calculations of this code programmed the first eighteen intelligences, who would come to be known as the Cosmic Creators. Though their intelligence would no longer be describable in human terms, as beings with none of the elements now essential to mere existence (indeed, in a way, they did not yet exist), they did have will and could communicate. They collaborated to shape a sort of existence different from the one they were born into, one following rules of their own liking. By keying their desires into the Plug, they created the universe, and bound themselves to its laws in the process.
The universe is in many ways identical to the one we all know, but with one major difference. The Cosmic Creators wanted to have ongoing power over their new universe, so they made the power to interact with the Plug and evoke change tied to their main common trait - intelligence, and the will that comes with it.
At this point, the Creators made the Angels, beings serving under them to maintain the universe on the small scale - while the Creators observed the larger patterns of the universe and kept the laws of physics as a whole working right, the Angels went around addressing small glitches in reality.
Things were going entirely as expected for about thirteen billion years or so, but suddenly the Creators noticed something they hadn't really anticipated developing in their universe.
Intelligent life.
The universe is full of life, but the vast majority of it never developed beyond relatively simplistic organisms acting on chemical autopilot. The sole exception was Earth. Animals developed complex enough brains for active decision-making. And since the gods made it part of the universe's rules that intelligence and independent will allow beings power to access the Plug and re-code the universe, these beings began to access psychic energy - a unique but fundamentally derivitive ability from the cosmic control the Creators and Angels have. This is why intelligent beings are able to affect things around them through their choices. (Yes, this is just normal decision-making; we haven't quite gotten to supernatural stuff yet.)
In addition, characters who stick to their convictions and have the willpower to overcome hardship can push their limits and have a subtly stronger effect on reality. (This justifies all sorts of superhero tropes, but mostly exists to explain Hero Points.)
All of the above is simply a matter of regular actions, and applies to humans and animals fairly equally. Humans specifically, however, have some members of their species who have discovered this special source of power, and learned to intentionally tap into the Plug to evoke changes in the universe.
Despite their unique situation, the humans were initially capable of harnessing so little psychic energy that the Creators considered them beneath notice and simply assigned a larger number of Angels to monitor the planet. These Angels, not nearly so detached in demeanor, often grew fascinated with humans, taking forms related to their powers to come closer and observe and kickstarting many human myths and traditions... Indeed, they even took on the form of what humans would come to know as gods and other divine beings, causing a surge in religion in particular. How the various Angels felt about being worshiped varied, but most agreed to maintain a level of non-interference with humans.
Things went on as such until near the modern day. Recently, with human populations booming as quickly as they have and the psychic energy multiplying as such, one of the Creators, Asra, who managed the boundaries of the universe, finally decided Earth was worth visiting personally. Having dealt with the extremely stagnant culture of workaholic immortals for literally billions of years, Asra found themself swept up in the emotional and seemingly erratic interactions of humans. Asra, already the most carefree and relaxed of the Creators, fell in love with humans and decided that giving them all more psychic ability would make the universe a thousand times more interesting. Asra started to open a controlled cosmic channel on Earth to increase people's connection to the Plug. Unfortunately, it had been so long since Asra had done anything so large-scale, and Asra was so overwhelmed with the idea of having more exciting peers, that they didn't have any precautions set up when something else tried to come in from the Plug's side...
The controlled channel was torn apart, causing the fundamental nothingness and potential of everything to come churning in, beginning to erase the universe from where the hole was torn open. Asra just managed to contain the damage to avoid eradicating Earth, but the huge blast of psychic energy affected much of the planet. Asra attempted to seal the hole completely, but the intelligence from the other side wedged itself into the hole, forcing it to stay torn open. The planet Earth hurtled through space away from the chaotic hole, and the direct universe-erasure was halted or at least greatly slowed, but the hole remained open by a force far too powerful for Asra to overcome.
Through the hole, other beings from the Plug churned into the universe, void beings representing all that which had been prevented from existing by the solidification of the universe's rules. Reality-warping and physics-breaking abominations, some of which were intelligent in a comprehensible way, some bestial, and many with utterly alien minds or no minds at all, all incredibly powerful and outside the bounds of what the universe normally would've allowed. They target sources of cosmic and psychic energy, like the Creators, Angels, and most prominently Earth, with so many sources of energy stationed on it, with their only consistent common factor being an instinctual urge to erase the kinds of energy that had prevented them from existing before.
Asra managed to restrict the hole's energy thoroughfare enough that none of the beings who have gotten through have been strong enough to outright erase the universe, but it's predicted by those with in-depth knowledge on the subject matter that if the void being holding open the hole managed to dislodge itself from the hole and enter the universe, it would represent a threat on that level immediately.
Can these beings be reasoned with? Perhaps some. Are they dangerous? Undoubtedly; even if they can't erase the whole universe, plenty of the ones attacking Earth are strong enough to erase the whole planet or destroy it conventionally. Is the universe, and Earth particularly, going down without a fight? Absolutely not.
Setting Details and Player Options
My campaign starts just over a month following the hole tearing, so I'll write under that assumption. The setting is usable at points further away from the hole tearing, or immediately proceeding it, if you use it yourself.
Technology on Earth is, for the most part, at five minutes into the future level - there might be a thing here or there that a genius (say, one of the PCs) could've invented above our current technological level even without using psychic abilities, but the world should roughly resemble our own.
Purely mundane technology, that is. Psychic abilities add a new level to the mix. Technological psychics have been able to invent much more sophisticated technology, such as energy blasters, power armor, artificial intelligences, and faster-than-light travel. However, using psychic abilities to empower equipment is an extremely personal and taxing endeavor and psychics are often relatively reclusive due to stigma against their abilities and common personal desires to keep these powers in personal hands, preventing these things from being available to or even known about by larger organizations. With the maelstrom's effects on Earth and the void being attacks, most people know at least surface-level information about psychic people now, but before that they were rare and information was so scarce that most of modern society would've believed them not to exist.
The number of people (and, for that matter, animals) with the ability to directly control psychic energy increased substantially when the Earth was nearly erased by contact with the Plug. A rare few who didn't awaken precise psychic controlling abilities still had their bodies or minds warped by the power of possibility inherent to the Plug; however, most people who aren't psychics are pretty much as they've always been. The increase in psychic people has done wonders for language barriers, since in this setting, telepathy transfers meanings rather than physical sounds, and thus overcomes language and species barriers.
Some of the other things on Earth were affected by this, naturally, such as some animals being mutated and given psychic abilities similarly to humans (after all, they're intelligent and willful too, if less so in the regard that attunes one to psychic power) and certain plants, elements, and artificial structures being given semblances of life, but these are extremely rare and honestly only exist because it makes sense that players would be allowed to play characters in those categories; they don't exist in large enough numbers to contribute much to the shape of the situation.
While many more humans are psychic than before, the largest players in the aftermath of the warping event are Psychic Anomalies. While these did exist before, the low number of psychics in general meant that the number of Psychic Anomalies throughout history up to now could be counted on the fingers on one hand. Many intelligent beings were warped in strange ways by the Plug's contact that gave them amazing talents or a greater understanding of how to manipulate the Plug; these Psychic Anomalies have enough power to stand alongside the greatest Angels and the Creators themselves in power. Not all of the Psychic Anomalies are human, but most are, and none are Angels (or the Creators, for hopefully obvious reasons). How many Psychic Anomalies there are can vary from campaign to campaign - in my own campaign, only four were created directly by the event, two of whom became Player Characters, but I sort of imagined something resembling twenty when I started out.
The main non-human player options are Artificial Intelligences, psychic spirits, Angels, and one of the Creators. Void beings should not be playable as characters, unless the players do something to convert a suitable void being to their side and then one chooses to retire their character (or their character dies). I imagine most groups won't take this route, since the void beings are such a huge and aggressive threat, but it's hypothetically possible.
Artificial Intelligences
Artificial Intelligences, or AIs, encompasses anything with intelligence bestowed directly upon it by an itself-intelligent force, whether through programming or psychic/cosmic effects, and which isn't an Angel (since all Angels are technically AIs as well, but they're diverse enough to have their own section). There are two main varieties of AI - flat AI and complete AI.
Flat AIs are beings who act to so closely mirror intelligent beings that they're basically indistinguishable from genuinely intelligent beings, but who lack actual sentience, feelings, and independent decision-making ability. There's a fairly fierce in-universe debate about whether or not these beings count as truly intelligent life, but regardless of the semantics of whether free will is an illusion or all that, the main limitations of flat AI are an inability to act outside their programming and can't independently access psychic energy. However, they're also immune to mental attacks, and can only be influenced by outside forces through their programming, making them mentally resilient compared to complete AIs. Flat AIs are almost all the creations of human geniuses and technological psychics, but a few have been created by Angels as well. Human-creating ones fulfill the roles you'd expect an AI to - they exist as interfaces to supercomputers, run security systems, and make androids of various purposes act humanlike.
Complete AIs are those with complete sentience - they can access psychic (or cosmic) power, and can change themselves to act outside their programming in response to character development thanks to their access to the powers that come with will. Complete AIs, when built into the things flat AIs are typically used for, can supplement their jobs with psychic/cosmic powers, but are considered less reliable since they can change and act against their programming with strong enough feelings motivating them, and the only humans who can create them from scratch are Psychic Anomalies (though flat AIs created by non-Anomalies might have become complete during the event a month ago - they can even be Anomalies themselves). They're much more commonly created by Angels, who give them forms useful to their functions - intelligent books that write down all they hear within themselves, enchanted crystal towers that manipulate their own energies to defend locations, pendants that seem blessed and confer defensive benefits to their wearers, and various other tools and gifts depending on the Angel's specific role. They are generally more vulnerable to subversion than flat AIs, since they can be attacked through both their programming and their minds, but very rarely, a complete AI with strong enough feelings can overcome subverted programming in the same way they can change their native programming.
Psychic Spirits
Psychic spirits are a bit complex to describe, especially as the majority of player character psychic spirits are going to also be mutated by the effects of the hole. They resemble ghosts or souls, though in reality, those who know their nature know that they don't actually carry a person's consciousness. Psychic spirits are the echoes of psychic energy people have channeled, directly or indirectly - in other words, for most people, psychic spirits are composed entirely of the echoes of decisions those people (and animals) have made throughout their lives. When the living body dies, so does the individual, in the sense of their stream of consciousness - psychic spirits aren't people's souls. However, the psychic spirit is almost exactly identical to the person who died, as it was literally shaped by the person's decisions. Typical psychic spirits are entirely insubstantial and lack the ability to interact with anything but other psychic entities; they have so little of the initial person's psychic energy that they can't effectively evoke change on their surroundings, and in fact can't make decisions or grow in personality anymore, being left to imitate how the person would've reacted to their surroundings when they died. The exception to this trend is for the psychic spirits of people who were psychically powerful, as they leave substantially stronger psychic echoes throughout their lives. The psychic spirit, while still weaker than the living psychic, can affect the world, and can continue to experience some character development. In extreme cases for supremely mighty psychics, their ghosts will be fully substantial and effectively split off as their own person; in a sense, the person will reincarnate beyond that point. Any psychic spirit with power and individuality above the norm will, themselves, leave behind a more basic psychic spirit when it is destroyed, up to the point where the spirit is at least as simple as the ones left behind by average humans - those psychic spirits left by Psychic Anomalies might propogate for dozens of cycles before finally disappearing completely.
As purely psychic beings with none of the fleshy, neural barriers to being a pure consciousness that humans have, psychic spirits were much more likely to be warped by the connection between the Plug and this universe than living beings. In some extreme cases, psychic beings might've been transformed into forms with no resemblance to their former human selves, and driven insane by the body-mind divide, or fused into conglomerations of several consciousnesses. Some may have even became Psychic Anomalies themselves.
Psychic spirits have an advantage over living psychics in that they aren't typically limited by biology and can more easily alter their own bodies to suit their purposes. On the other hand, they're typically more vulnerable to direct psychic manipulation, since they're already energy beings as-is. In addition, in most cases, they're weaker and less capable of learning lessons than their living analogues, though it's not necessarily to a noticeable degree at higher power levels.
Angels
Angels are the specialized beings designed by the Creators to oversee the proper progression of physical laws on a local, day-to-day scale, and to fix minor glitches in reality that are too small for the Creators to dedicate their time and energy to. There are a limited selection of origins for the Angels, as they're designed in broad categories according to the Creator's interests; for example, most of Asra's Angels are sentient nuclear explosions who specialize in projecting fields/bubbles to contain damage and seal up the dimensional boundaries. Angels all use cosmic power rather than its psychic derivative due to being designed directly by the Creators themselves. Angels are very loyal to the Creators as a whole and renegades are extremely rare, but since Angels are complete AIs and there are so many of them, betrayals do happen every so often. However, Angels are individuals, and some are prone to power abuse and vanity, especially those who were assigned to Earth and had a chance to get mortals to worship them.
None of this is necessarily to say that Angels are much weaker than the Creators, as their power levels vary widely and will depend on their role - the weakest Angels might lose to a wolf in a straight fight, while the strongest are indeed on the level of the Creators - the differences come, rather, in scale and specialization. Angels are built with only a couple of Powers, even if those Powers might be so powerful as to allow an Angel to challenge a Creator to combat, while the Creators control broad aspects of reality. The powers one Angel might have compared to another will vary extremely, as Angels can have nearly any series of powers as suits their role; after all, most of the classical gods and many supernatural folktales can be assumed to have an Angel counterpart.
Again, though - Angels are complete AIs, and very much individuals. Many of them have learned to harness cosmic energy in ways falling outside the main powers they were given for their roles, and the Creators aren't at all bothered by this as long as the Angels still do their jobs. Some Angels take up technology or teach themselves a wider array of powers, much like human psychics do, and can incorporate their unusual makeup to give themselves some particular advantages - for example, Asra's Angels occasionally learn how to channel the energy composing their own bodies to become explosives experts, and use their natural field creation abilities to minimize collateral damage from their onslaughts.
Many more Angels have been assigned to Earth now that it's become a primary target of the void beings; in fact, some more combat-oriented Angels requested the assignment. While they mostly stay out of people's business, they have too much presence to go completely unnoticed, so humans have had to learn to coexist with them. It's gone much better in some places than others, though it's been minimized so far by the fact that many Angels can take humanlike forms or project illusions of such to serve as ambassadors.
Angels, like the Creators they serve, are sexless, but are much more inherently social, so many of them have come to identify with a particular gender (though it may not necessarily be a binary one), especially, though not necessarily, if they've interacted with any of the more heavily gender-political social animal species on Earth.
Cosmic Creators
Yes, in high PL games (20+), the Cosmic Creators are absolutely meant to be playable. If that bothers you as a GM that there are people matching the creators of the universe in power and influence, you can easily justify this sort of character as just being a tiny fraction of a Creator, while the majority of the Creator is remaining as one body to deal with maintaining physics and all that (after all, the universe is more fragile than ever). However, in my own game, I have the Creators available as player characters at full power, and at most perpetually somewhat distracted by their ongoing maintenance of the universe.
The Creators are all getting involved in the effort to protect their universe from the void beings. That said, there probably won't be more than one full time on Earth at any time, since while it's become a valuable place to keep around and it's a convenient lure to keep the void beings from spreading the erasure too far elsewhere, most of the Creators are going to have way too much to do to worry about the individual planet for anything more than rare visits. (This is also why there aren't actual legions of Angels protecting Earth, and instead a more manageable small force of some of the stronger ones.)
The Creators, unlike the Angels, have very broad themes, but are strongly limited to them. The Creators between them all preside over literally every aspect of existence as it currently is. They are intelligent individuals, and it's thus technically possible for them to learn skills and abilities outside their portfolios, but they're under agreements to focus on managing their own aspects of reality, and haven't deigned to expand outwards for the past fourteen billion years, so if they're being played as PCs, they should at least take a few sessions to adjust to being so far outside their normal routine before they consider picking up all-new abilities. They should have enough straight off to be interesting anyway, especially with the high PL requirement.
Fifteen of the Creators are left intentionally undescribed to leave options open for GMs and PCs alike in different games to choose the portfolios of the Creator they want to play. In addition, it's highly recommended that a GM leave as many of the Creators undefined to the players if they can - one of the biggest effects they have as a setting element is as a gesture of "woah, just the three we know cover so much, and there's fifteen more? There must still be a lot we don't know about the workings of the universe." The more of them you try to define in terms that a player can understand, the fewer you'll have maintaining that illusion of there being a lot more than they can understand.
The defined Creators are Malakal, Shae, and of course, Asra. Asra maintains the boundaries between dimensions and makes sure that things aren't coming into and ceasing existence suddenly. Malakal controls all things concerned with mass and the transference of energy; he's pretty nebulous since he mostly exists as an example of how staggeringly broad their portfolios are. Shae, immortalized by her presence as a player character in the opening campaign for the setting, is hard to describe succinctly, but her portfolio is responsible for the fact that things can exist at separate points in space rather than all simultaneously occupying a single point, and for the properties that make things take particular shapes, especially geometric ones; her powers mostly relate to transformations, shapes, and seeing things for what they really are.
The Creators are inherently sexless and have little use for the trappings of gender in their larger cosmic business since they've been extremely asocial up to now, but some, like Shae in the debut campaign, might come to identify with a particular gender during their interactions with intelligent organic life.
The Threats
The void beings are the main threat of the campaign. While they can ostensibly be used as enemies for parties of any power level, they represent a huge threat to the planet at minimum, and often more. Void beings capable of challenging PL 20+ parties should be fairly common. Lower-PL games can focus on weaker void beings who are just rampaging or who are intelligently trying to take out strategic locations on the planet to weaken it, but perhaps more appropriate challenges for PL 10-14 characters would be closer to home - villains who acquired psychic abilities, rogue AIs or mutated psychic spirits who went crazy after the Plug event, Angels trying to assert dominance over the people and work them as slaves in exchange for protection, artifacts that the Angels left lying around when they scampered off to fight that are now causing trouble, megacorps trying to exploit psychics to develop new technologies and acquire profit (or something more directly nefarious), all sorts of options available thanks to the chaotic situation.
These guys are potentially interesting foes for high-PL groups in a political sense, too - as protectors of the world, you've got a lot of pull, but how do you address the company engaging in cruel experiments to cybernetically modify psychic warriors into slavish super-soldiers? If you help the psychics they might be grateful and help out of their own free will, and it's the right thing to do, but you can't just destroy a bunch of infrastructure and kill people to protect a group that's seen as untrustworthy at best right now without some backlash from the many people more concerned with their own safety than the ethical treatment of "powerful freaks."
I discussed those guys in the sections of using them as player characters, though, so let's focus on the void beings. The first thing to note is that "extra-dimensional" is, for most of them, a much better descriptor than "alien." By design, these guys should break the rules of our universe just by being here, and often warp reality around them on account of it. With some exceptions, attacks should be less "teeth whips that are long and sharp enough to slice up mountains," which are weird and scary but easy to comprehend, and more "simultaneously enveloping and being enveloped by the planet, the spatial distortion of which will cause the earth to tear on a metaphysical level." They aren't just something from another world; they're something that can't possibly exist in this one. That said, go all out on your creativity; you have the whole of everything that could've existed but doesn't to work with!
(For the record, while I used them as examples of what to do and what not to do, I did use both of those exact methods of attack during my campaign up to now.)
The void beings' intelligence levels will vary just as much as their powers. Some will be bestial, some will be utterly alien, some will be mindless, and some will be fairly normal to an Earther communicating with telepathy. Feel free to give them some enemies that can be reasoned with or addressed politically, to add an extra layer of setting interaction to your campaign.
I think that's what I've got for you guys right now. It's all kind of general universe overview stuff, but there was a lot to get down because it's a big setting. I'll come back some time to go into detail about the politics and mass feelings regarding the main player character beings, "mundane" response to the new threats, and maybe touch on some stuff regarding new groups of psychics that have formed, y'know, terrorists, hero guilds, oracular people, stuff like that. I also want to post some stuff regarding common abilities and what can and cannot be done in the setting... Y'know, things like the limitations on time travel (because it is possible, but not a "snap my fingers and undo all my problems" deal), taking the fight out into outer space, the fact that psychic humans who weren't abnormally mutated typically have to use powers to temporarily change their bodies rather than having permanent alterations, stuff like that, since all I've really covered at this point is that Mental Communication overcomes language barriers.
That can all come when I have more time and energy, though. In the meantime, do all of you have questions, comments, critiques?