Riverworld

The fictional planet Riverworld is the setting for a series of science fiction books by author Philip José Farmer, published between 1971 and 1986. In Farmer's books, all humans (and pre-humans) are reconstructed on a giant artificial planet called Riverworld. The books explore interactions of individuals from various cultures and time periods. The underlying theme is quasi-religious, with the author examining the motivations of alien intelligences operating under ultra-ethical motives.