Let's imagine the golden age of the superheroes, the old Hammer horror movies from 30's-40's but also the modern nightmares like the saga Hellraiser, Kult: Lost Divinity, Wolfenstein Castle, Doom Eternal or Mortal Kombat.



There is a demiplane as a Dyson sphere, with lots of planets (but the gravity forces can't attract them each other and the distance between those worlds is relatively constant), and meteorites with carvorite, a special, and expensive, mineral used for anti-gravity vehicles. Almost all the big astral bodies have got, or had got, biosphere (life and ecosystems with living beings).



All contact with the deities was lost after a second titanomachy, a war between gods and the primal titans. Now the lord feys are the new "spiritual guides". Their agents are the lictors, fae beings with fat bodies and metallic thorns on their skin and the power to summon and control the fasces, a weapon composed by a bundle of thin tendrils forming together a stronger tentacle, as symbol of the union makes the force (united stronger than divided).



The demiplane is a prison of powerful beings who are cursed to the reincarnation as mortals forgotten their all past lives. The lictors are the jailers.... or maybe this is a trick and the jailers are the true prison but they are too busy with the masquerade and the fight for the power to notice, who knows?



They are rumors about abductions by aliens from outer demiplane, and conspiracies about infiltrations by aliens among high spheres. Other voices talk about cryptocracies, secret societies, maybe ruled by vampires or some powerful supernatural faction. The most of governments are dictatorships, hereditary monarchies (most of times puppets of creatures as giants or dragons), or fake democracies where politicians are only figureheads obeying orders by secret lodges.



The space race has just started, and almost the digital age, but the mining resources were too poor for a complete revolution industrial. There is a strong technophobia among people because some cases of machines controlled by paranormal powers have been reported. Magic allow to avoid this, but magictek or arcane technology is more expensive. And after using modern technology (but magictek) to attune to magic item is harder. Alchemy has allowed the discovery of new materials as the graphene or biofuels. There is a strong investigation about the bioregeneration, growing plants with toxin resistance to help zones tainted by industrial pollution (or defiler magic).



The gunpowder is known, but it isn't too useful in the battlefield because mystic powers don't allow. Once there was an attempt to use a nuclear bomb for a war, but in the last moment the divine powers used teletransportation magic to send the weapon against the attackers. It was the first and last time a nuclear bomb was used. The temples in the cities and towns can create a magic effect to block or punish the firearms. The criminal would rather to use hand crossbows what can reload itself. There were reports about planar gates linked to the Valhalla to send petitioner warriors with bulletproof traits to punish the firearms in the battlefield. And the usual battlefield is trench warfare fighting against monsters with bulletproof skins and remote-control by means of spell-like effects (in the real life the crocodiles have got a hard skin enough to endure light ammo). There is like an arm race between spellcasters and gunfighter. Usually gunpowder is cheaper than magic, but this has created new tricks (for example a piece of ectoplasm to block cannons, or illusory magic like smoke grenades).



* My idea is to allow different type of stories. If you want to be an one-man-army like Rambo or other action hero from 80's movies you can, or weird western, or an anti-vampire crusade, or a post-apocalypse zone where superheroes became psychopaths by fault of a Lovecraftian cult who created a monster as a trap and biological weapon to infect them. If you want you can use all the monsters from World of Darkness and use the cities like a Jurassic Park for Hammer films creatures, or a secret invasion by skrulls, or the "visitors", the lizardmen from V (a famous 80's serie and an allegory about the rise of the nazism. The remake wasn't not very successful).



The time travel also is possible, well, not really and then you haven't to worry about paradoxes. The "past realm" or time spheres really are like a theme park or backup copy in the space-time continuum, an akashic realm, created with the memory by the collective (the past as it's remembered, not how happened really). It is as if you send your PC of Warcraft to the server of Warcraft Classic. You don't travel to the past really but a copy of the past. (Do you know the Hollow World, a Mystara spin-off?)