Crossovers are a time-honored tradition in media, going back to the ancient Greeks (remember the Argonauts?) at least. The intertwining of genre literature characters hit its high mark with the so-called Wold-Newton Universe. What Philip Jose Farmer created to give a give illustrious pedigrees to Tarzan and Doc Savage, others have turned into a grand unified theory of crossovers.
The appeal's obvious to any genre fan. If the Shadow meeting Doc Savage is good, throwing in the Cthulhu Mythos and Shaft might just make it better--particularly if a way to really explain all these characters existence in the same universe could be found.
“Anything (or almost anything) goes” crossovers can have a lot gaming appeal. Superman can join the Avengers in a supers game. Philip Marlowe or Sam Spade might cross paths with investigators in Call of Cthulhu. Or maybe its apes versus machine, as Escape from the Planet of the Apes meets the Terminator.
Crossovers can also be used on a smaller scale to create setting continuity. PCs from one game might show up as NPCs in another, or events from a previous game might be referenced. This can even work cross-game and cross-genre. The Hyborian Age of Conan was long part of the prehistorical past of the Marvel Universe, so there’s no reason one’s D&D game could be somehow related to the history of one’s superhero game, or even one’s modern occult game.
All this just scraps the surface. Anybody have any crossover examples from their own games?
8 minutes ago