Fantasy

With the presence of powerful magic and god- like beings, magical analogs of the technological megastructures are certainly possible. In fact, the GM can let his imagination go wild in creating these sorcerous variations, which, unlike their science-fiction brethren, don't have to hold themselves hostage to the restrictions of the laws of physics. In a high-fantasy world, O'Neil-like colonies may be created from enormous, self-sustaining magical trees, or a Ringworlds may have been created by a pantheon of gods with each sector being a particular deity's domain. In the Spelljammer setting, it was suggested that Crystal Spheres which surrounded entire solar systems were created by long-vanished ultra-beings to preserve the magical integrity of the cultures and deities there.

A more intriguing approach would be to mix technological structures into a more magical settiing Perhaps they would be the few remaining remnants from a far more advanced culture that met with a disaster or another, or perhaps the campaign world is being visited by technological aliens who want the structures for their own inscrutable purposes. An infinitely high tower the PCs hear rumors about may actually be a space elevator, or the arch-like Valhalla in the sky that the party has been told their souls will one day travel to may actually be a planet-grinding orbitville.

Finally, truly ambitious GMs could set a fantasy, campaign on one of the larger megastructures, like a Ringworld or a Godwheel. One of the central features of such a campaign would be the PCs puzzling out and confronting the true nature of their world, and, of course, the sheer scope of the megastructure would allow the GM near-infinite room for expansion.

Superheroes

Want to humble a party of PC heroes who have perhaps gotten just a little too powerful and cocky for their own good? Throw a megastructure at them. If Heap o' Muscles Man thinks he's pretty hot because he can heft a tank or two, confront him with the legacy of beings whose housing projects were on the scale of planets and stars and beyond.

Encounters with megastructures are more fitting for the "epic" kind of hero, like Superman or the Fantastic Four. Discovering, exploring, and dealing with the inhabitants and builders of a megastructure could be one of their ultimate adventures.

Comic books have occasionally made use of megastructures. Galactus, a Fantastic Four foe, had a home base so large that planets orbited it. A Dyson Sphere was briefly mentioned several times in the X-Men Comics, and Superman visited Warworld, a converted planet. The very best use of a megastructure in a superhero universe, however, is the previously mentioned Godwheel, in the various titles of Malibu Comics' Ultraverse books, especially the mini-series Break-Thru and Godwheel. In fact, super-beings ("ultras") arose on that Earth as a direct result of the intervention of explorers and artifacts from the Godwheel. The two sides of this Ultraverse Godwheel were forever isolated from one another, and gave birth to wildly divergent civilizations. On one side a series of advanced, technical civilizations arose. On the other, high technology was unknown but magic dominated every culture that came into being there.

And Beyond

Science fiction has often been called the genre of ideas, and at no time is that more apparent than when discussing such mind-boggling concepts as megastructures. Whether used as background, adventure settings or the basis of an entire campaign, megastructures will help to add a true sense of wonder to your RPG universe.

MegaStructures Sci-fi Settings That Challenge the Scale of the Universe

Introduction
Free-Floating Structures
Planet-Centric Structures
Star-Centric Structures
Other Genres