The past is never dead. It's not even past.
Your players are itching for a new campaign. You've played heroic fantasy, space opera, gritty urban fantasy, cyberpunk, sword-and-sorcery barbarian fantasy, military science fiction, dark fantasy, umm . . . sensing a pattern here?
Maybe it's time to try something different. Why not roleplay in a historical setting? Like, the history of Earth, a place we gamers actually live on and can learn about. I know, we don't have any orcs, necromancers, dragons, deckers, zaibatsu cops, or sapient AI. But Earth does (or did) have marauding Scythians, Cardinal Richelieu, jaguars, dashing aviators, the Gestapo, and Shaolin monks. Think about never having to draw in rivers and mountain ranges on a map: they're already there, complete with believable weather and a full ecosystem. Names for NPCs, personalities of important leaders, recordings of contemporary music, and event timelines are all as close as your computer.
Some historical figures led lives so improbable that they'd never be believed in fiction. Think of Archimedes, a brilliant philosopher and mathematician who invented siege engines to defend his home from the invading Romans; Eleanor of Aquitaine, who brought her ladies in waiting on Crusade and led a revolt against her husband ; Ashoka, the Indian king who led great conquests in his youth only to later embrace Buddhism and create great public works; John Dee, who effortlessly combined science, astrology, and back-room politics in Elizabethan England; Hypatia, the last librarian in Alexandria, murdered by early Christians; and Marie Laveau, a Creole woman who gained significant power in 19th-century New Orleans through her Vodoun ceremonies and network of informers.
Now that you have some idea of the potential of historical characters, what to have them do? They could explore India and Africa with Chinese admiral Zheng He, decades before the great European explorations began. They might get rich in the rough and tumble world of early financial markets. They could even fight in the Battle of Thermopylae, though if they're playing Greeks that would probably be the climax of the campaign.
Want to read more? See here for an explanation of the roleplaying hobby or here for an example of developing a specific historical setting for gaming.