by Jeff Vogel, a small indie game developer, as having influenced the design for his game Exile: Escape from the Pit, saying that while most of the game's plotlines were his, this classic short story helped shape his ideas. References Sources Peter Nicholls. The Encyclopedia of Science Fiction. London: Roxby Press Limited, 1979. . Clute, John with Peter Nicholls. The Encyclopedia of Science Fiction. New York: St Martin's Griffin, 1993 (2nd edition 1995). . External links Short stories by Robert Silverberg American science fiction novels Novels about time travel Novels by Robert Silverberg 1967 short stories 1968 American novels 1968 science fiction novels Works originally published in Galaxy Science Fiction Doubleday (publisher) books