Numenera is set a billion years in the future. Civilizations have risen and fallen on Earth. Even though the current inhabitants live at about a Medieval level of technology, the leftover remnants of these advanced societies lie all around them. Some of these are extremely helpful: advanced tools, valuable means of communication and learning, transportation, defenses, and weapons. Others are dangerous: genetically altered monstrosities, flesh-warping radiation, creatures transplanted from distant stars, and clouds of out-of-control nanobots, just to name a few. This setting, called the Ninth World, provides all manner of opportunities and challenges to those that call it home.
The game system that drives Numenera is meant to be fast-moving and simple, so that it facilitates the stories the group wants to create, the imaginative places and creatures the GM needs to describe, and the mind-blowing ideas the world encourages. Everything in the game is designed with these goals in mind.