A deconstruction, of sorts, of the DC comics universe (before it got all EXTREME and stuff, anyway)
In this world, humanity is living through a Promethean Age, in which all things seem possible. Superheroes started showing up in the 1930s, and have increased in number ever since, as simultaneously contact began with multiple alien races and ancient mystic forces awoke from their ancient slumber. Today, there are thousands of superheroes: some having gained their powers through extraterrestrial science, either from aliens or human duplication of said technology: some through the intervention of mystical beings: some through the use of ancient alien super-gadgetry, some through being aliens themselves, and some through the use of the mystic "Mentad" training that allows the unlocking of the true mental potential many humans have ever since the Great Old Ones meddled with the genetics of primordial ape-men. Those are of course only the "proper" superheroes: there are tens of thousands of non-superpowered Masked Avengers, cyborgs civilian or military, adventurers, talking animals, and civic-minded robots (after all, it just took a theme song, cape, crown and goggles to make a foul-mouthed robot into Super King). Supervillains, evil mad scientists, etc. are equally common, although somewhat less flamboyant nowadays, given the government's "orbital death-beam them first, question them later" attitude towards anyone showing up atop a giant robot and aggressively monologing.
Gods and spirits are real, as they always have been (belief + the Spirit Of Man leads to the birth of Gods, which although fading with time never die off entirely as long as anyone remembers them) but they prefer to act from behind the scenes rather than visibly interfering in human affairs (for one thing, that might lead to getting their butts whipped by superheroes).
Earth has diplomatic contacts with over two dozen alien races (and as many more have contacts with individual governments or even private individuals, often in secrecy) and wondrous new technology is everywhere, if somewhat unevenly distributed. On the moon, the Justice League strives to protect humanity from menaces both local and alien (and incidentally runs one of the world's largest centers of technological research).
The Justice League is headed by the most powerful hero on earth, the Last Son of Krypton, Superman. Active since 1938, at nearly 100 he is only slightly touched by age, a few wrinkles around the eyes, a touch of grey at the temples. His wife, Lois, only 5 years younger, still looks pretty good, although an embarrassingly high percentage of her now consists of synthetics, cloned organs, and cybernetics, including built-in force-field generators and other super-kidnapper bafflers. Ambassador to the stars, savior of multiple planets on one occasion or other, Superman is known halfway across the galaxy.
Less well known is the Mystic Council, headed by the mighty Spectre and Dr. Fate: they meet in an ancient temple in the Himalayas, hidden by magic from prying eyes. They handle supernatural menaces: which however does overlap on occasion with the brief of the Justice League, for some evil gods and ghosts and demons and bump-in-the-night critters do come from space, and some alien races use magic as much as technology - or wield weird forces that cannot be precisely be classified even by the mightiest of terrestrials.
The Teen Titans are now on their third generation of Titans. Batman is retired and kept alive by some formidable (and not yet government-approved) cybernetics and biotech, but behind the scenes still is the leader of the now vastly extended "bat family", and has made Gotham into essentially the world's largest gated community, an electronic Panopticon which, depending on who you ask, is either a paranoid nightmare or a paradise on earth. Wonder Woman, Plastic Man, and other immortals remain much the same as fifty years ago, although Paradise Island now suffers from the horrors of a younger generation fascinated by the music and TV of "Man's World".
Although the Nazis and Japanese were able to gather some formidable forces of their own, including the powerful Spear of Destiny, and gather their own superheroes and petty Gods, in the end the "superpower gap" was too great, and WWII ended early, with rather less dead Jews and an Iron Curtain rather further to the East than OTL. (Admittedly, finishing off the Nazis took rather longer: rooting out the last Nazi flying saucer bases and Hitler clones and mystics with armies of the SS undead took until the mid-50s).
China and the USSR remained rather closer than OTL, and deals with aliens and a bit of black magic has kept the USSR afloat, although the Chinese finally broke with the USSR when a deal with the Reptoids of Altair V nearly led to the population of the Red Block being replaced by Replicants in the mid-70s.
The USSR is now essentially a technocracy, and although still a one-party state, has largely dropped the whole "conquer the world" thing and now seek to Soviet-ize outer space, having colonies on Mars, Venus, the moons of Jupiter, and in a couple of nearby star systems. (The last are a bitch to re-supply, since star drives are horribly energy-expensive - antimatter power sources aren't safe, and quantum flux power sources are _expensive_ to build and maintain. Lex Luthor developed his own star drive back in the 50's, but since it was powered by robbing the earth of a measurable part of its angular momentum, it hasn't caught on).
The solar system is being colonized by a number of powers. Mars is dry and cold, but approximately as habitable as Siberia, and filled with interesting ruins from the final genocidal war between the White and the Green Martians tens of millenia ago. The Martian Manhunter has a summer cottage of sorts on Mt. Olympus - he's very closely involved in the excavation of his civilization and the possible dangers thereof. (He has recently married a Martian girl from an alternate universe where the Greens survived, but they've agreed to put off kids for another century or so.) Venus is toxic jungles, strange drugs, and weird, dangerous ruins of a cyclopean, Lovecraftian sort. The the various races of Saturn are odd to the point of incomprehensibility, but they are mostly harmless to visitors.
"Economic reform" doesn't really work as OTL in this world, since scientific progress has been much faster: government economic controls and technology controls are universal, because the Markets are always being disrupted by some new "wonder" technology which then has to be somehow fit into the preexisting setup. China (led secretly behind the scenes by the immortal Fu Manchu since '79) has gone from a desperately poor peasant country seventy years ago to a country filled with towering skyscraper cities, fusion power plants, super fast levitating monorails, and bases on other planets - and hundreds of millions of poor peasants, which have not yet been educated and trained up to this new world, and consequently do a lot of shit jobs that in some rich countries are now increasingly being done by robots.
Technology is similarly unevenly distributed world-wide. New batteries allow a car to run longer than it could with a full tank of gas, but the flying car, although technologically possible, is forbidden in most countries because computers smart enough to handle rush-hour traffic have an annoying tendency to become sentient. Technology that can keep you going for a couple of centuries now exists, but is too expensive for Blue Cross, and is in any event inferior to magic for keeping yourself alive (although such magic, in turn, usually involves costs higher than the merely monetary).
In fact, alien technology exists that _could_ give people cheap immortality, but the Justice League and the Mystic council suppress knowledge of it - both quantum computer analysis and mystical divination indicate that introducing immortality to humanity at this point in their development would be disastrously bad. At least cancer, heart disease, and senility are now easily curable. (Although alien diseases still kill thousands every year, and if it weren't for the secret presence on Earth of the Regulus Purple Circle (think the Red Cross, Iiin Spaaace) epidemics could kill billions).
Virtual-reality addiction is a serious problem in many advanced countries: the Illegal Alien Tech department of the FBI and similar organizations abroad rivals the Drug Enforcement division.
Robots are common as dirt, and illegal celebrity cloning is passe. Cyborg "a la Anime" armor is now fairly standard issue in the armies of major powers, and even grunts in India or Brazil now at least tote death rays. (Lasers and ion beams bounce off Superman's chest just as harmlessly as bullets used to, though). Biotech is not quite as advanced - the application of alien biotech to the evolutionary Rube Goldberg device which is the human body is still tricky. This world's version of Stephen Hawking, as the result of a too early effort to cure his nervous degeneration, is now a grotesque, twisted parody of a human being who, on the plus side, can stay up drinking and dancing till 5 and still be fresh as a daisy at 8. (And he gets the chicks, too: this is, after all, a world full of freaky looking people, aliens, intelligent machines, and various sorts of Undead, not to mention cybernetics fetishists, bio-modified "furries", and even creepier stuff. Women tend to have broader standards).
Some adjustments have been made due to the problem of the occasional super villain rampage: quite a few people have gone in for living underground, others just move to the 'burbs, even more widespread than OTL. For those who still live in city centers, the shiny skyscrapers of the great metropolises are made with ultra-strong synthetics and complex basket-work skeletons so massive energy blasts and invulnerable bodies flying at several thousand miles an hour just punch holes through without collapsing the building. (The USSR, OTOH, is into fancy planned cities in spite of potential for damage: it does, after all, have a "zero tolerance" and "disintegrate lawbreakers on sight" policy for any super beings, good or bad, not under government employ. Only a few of the most powerful and psychopathic of villains would dare throw down in Soviet cities).
Magic is more obscure than super-tech, and less familiar to most. It derives from unseen and other-universal Powers, its users are not in the least interested in having it commercialized, and are quite pro-active in suppressing those who feel "information should be free". (Still, there are occasional slip-ups: disaster was narrowly averted after some SOB put the complete text of the Necronomicon on the internet).
There is a lot of "superpower envy." Few people have the money to become powerful cyborgs or get cutting-edge power armor, few have the time and the fearsome mental discipline needed for Mentad training (and for those who do have it, many lack the genes), and even fewer can find a wizard or sorceress willing to take them on as an apprentice, or know how to find an actual Grimoire. Still, people try: a great many every year die from exposing themselves to exotic radiations, get lost in the jungle trying to find the secret city of X or Y, and get admitted to hospitals with bad infections arising from the implants of on-the-fly cyberneticists. Quack "become a superhero" courses abound, and the few which _aren't_ fakes are either horribly expensive or horribly dangerous, or both.
The death penalty is pretty much universal with respect to the use of superpowers to murder. It only took a couple of wrecked cities before even the most liberal accepted the reality of the situation. (The Joker was shot in the head by a police sniper back in 1950. The jury accepted his "my finger slipped" excuse).
Lex Luthor is currently building an interstellar empire on the other side of the galaxy. He plans to return to Earth and conquer it eventually, but he wants to make sure that for once he has all his ducks in a row. (After terrestrial governments killed the last two Luthors trying to take over the world - a cybernetically controlled clone and a brain-washed duplicate from a parallel world Luthor-prime knows the stakes if he loses).
A number of countries in Africa, SE Asia, the Middle East, and S. America are run by mad scientists, wizard kings, or secret societies. Due to the potential for Mass Destruction inherent in driving such people into a corner, they generally exist on a basis of "don't try to take over the world and we won't send in the superheroes", (besides, especially in Africa, they often do a better job than the governments they replaced). Some of these are actual countries (Burma), others states carved off from pre-existing states (the Black Colossus's Equatoria Free State) or ones that do not exist at all in our world (such as the small kingdom of Markovia, located where Austria and Slovenia intersect in our world). There is also a republic of Transylvania.
Other diplomatically recognized states that do not exist in our world include Atlantis, Aquaman's undersea kingdom and their ancient rivals in Mu, beneath the Pacific, along with a couple of underground kingdoms and a no-longer-hidden-city or two. (The sapient gorillas, whose city is disguised as an ancient basaltic eruption in the Ituri rain forest, do not have UN membership: they prefer to maintain their privacy).
There is no world government, but in the face of alien threats and increasing off-world colonization, there is a tendency for human beings to huddle together. The US, EC, Japan, India, and democracies in Africa and Latin America are more closely tied together than OTL, and are working cooperatively to colonize space and fight super-crime and build planetary defenses. The technocratic and somewhat post-humanist USSR stands a bit apart, as does China - as for the Islamic countries, if you thought Islam was having trouble adapting to modernity OTL, you ain't seen nothin'! Super-powered Jihadists are a serious problem.
In the meantime, the mystics and spirits and mages worry. One reason that the earth has become such a remarkable place lately is that the Conjunction Of The Thousand Spheres is nigh: the forces of magic and chaos flow strong, awaking many forgotten powers and easing the transit of higher space for star travelers, but it also weakens the fabric of reality, and across the galaxy looms the possibility of a fresh cycle of war between two worlds, one in the calm dark at its very edge, the other near the galaxy's glorious but radiation-sleeting center: the World of New Genesis, the realm of the New Gods, and Apokolips, the realm of the ancient evil known as Darkseid.
Super-battles and the plots of mad scientists are an ongoing problem, but it doesn't kill any more people than are killed in automobile accidents in our world, and most people are relatively unflappable. (The existence of the soul has been scientifically demonstrated, which is somewhat reassuring). Given that superpowers can happen to anyone, in spite of the aforementioned "superpower envy", there isn't too much hostility to the super-powered, which are in many cases considered "lottery winners." In spite of all the magic stuff, a lot of people are actually fairly irreligious, in a classical Chinese way: they are aware that there are a great many gods and demigods in the universe, but they don't really see much point in revering them unless there is something in it for them.
Just an effort to put five minutes (no more! ) of thought into what a superbeing-filled world might be like...
It reminds me of a short GURPS IST or Wild Talents.
I still hope you will one day make a Marvel world.
It wouldn't be THAT different. The big difference is the Marvel universe's distrust of people who are born with superpowers, rather than gain them.
If only comic book companies would take a long view like this and stop starting over every few years. Alas...