This is Torg:
A dozen separate universes, each called a cosm, each different from all the others in fundamental ways. One is a cosm of High Fantasy, where magic is real — including dragons, magicians, and enchanted blades — and the Honorable fight the Corrupt. One is a Technohorror cosm, where cruel technodemons rule an enslaved humanity. One is a Pulp Supers cosm, where costumed heroes fight costumed villains, gangsters drive Duesenbergs and carry tommy guns, and an insane master villain plots to conquer yet another world. There are many more cosms, one of which — called Core Earth — is just like our world.
Each cosm has different axioms: Magic, Social, Spirit, and Tech. Each also has different World Laws, which describe ways in which each is unique, mechanically and mentally. Together, these comprise the cosm’s reality.
These cosms have each invaded the real world, conquering parts of it and enforcing their reality over our own. The rulers of these invading cosms are High Lords, powerful and immortal beings here to drain Earth’s Possibility Energy, the energy of existence. Without our Possibilities, our world, our cosm, will die.
Players are heroic Storm Knights, rare individuals who can cross the roiling reality storms at the edge of the invader’s realms. They come from all the cosms, and are as different from each other as their cosms are. Yet they are all united by one goal: to defeat the High Lords and free Core Earth.
In Torg, a noble knight, wielding the power of his gods, and a cyber-enhanced sneak thief can team up with Captain Heroic to fight bloodthirsty dinosaur-men in a primitive jungle. They can fight dragons in the magical reality of Aysle, scavenge for lost technomagical relics in one of Tharkold’s devastated and decayed cities, stop the insane Doctor Dimension from vaporizing Cairo with his dastardly Omni-destructor.
They can be from a dozen different realities, and can adventure in each of those realities. They can chase a villain across the globe, crossing from fantasy to cyberpunk to technohorror, all in the same game session.
This is Torg: trans-genre roleplaying across many different realities, fighting to save the world.