Roleplaying game inspired by Larry Niven's Ringworld and Known Space series. The game was created by John Hewitt?, Lynn Willis? and Sherman Khan?, Greg Stafford?, Sandy Petersen?, Rudy Kraft?, Charlie Krank?, Ed Gore?, and Jeff Okamoto?. Chaosium published the game in 1984 and a Companion Volume was also published for it in the same year.
The RPG has a set of 4 sourcebooks - The Explorer book, The Technology book, The Creature book and the Gamesmaster book all published in a boxed set with the cover art by Ralph McQuarrie? (who did most of the preproduction art for the first three Star Wars? film, A New Hope?, The Empire Strikes Back? and Return of the Jedi?).
The setting is a distant future based on extrapolation of as much hard science as Niven had available. Specifically, it's the 29th century. "Known Space" (also the commonly used title for Larry Niven's future history science fiction series) is about 80 light years in diameter with 10,000 stars, including Human Space (40 light years diameter, 524 stars in 357 systems, 30 billion humans, ⅔ on Earth), as well as neighbouring Alien civilisations. Important Alien civilisations include the Puppeteers, paranoid pacifist herbivore centaurs, and the Kzinti, carnivorous warlike felines, who fought multiple wars over hundreds of years against the Humans, being defeated each time. Human allies include intelligent dolphins and orcas.
"Known Space" only serves as a background for the game. The game is intended to be set on the Ringworld itself, an enormous single world discovered at the far reaches of Known Space, a ring around a sun at approximately the orbit of the Earth. It is 997,000 miles wide, about 125 Earth-diameters. The total inner surface of the ring is equal to that of 30 million Earths. The ring is spun at a speed to provide 0.992G of gravity on the innerside, while 20 giant shadow squares at about the orbit of Mercury occlude the Sun to provide night. It was constructed by the Pak Protectors, now mostly extinct, who had a common origin with humans. The Ringworld is home to some 30 trillion sentient inhabitants from up to 2000 hominid species. The world is described in a series of novels by Niven, Ringworld, The Ringworld Engineers, and, after the game's publication, The Ringworld Throne and Ringworld's Children.
Information from the RPG, along with notes composed by RPG author Hewitt with Niven, were later used to form the "Bible" given to authors writing in the Man-Kzin Wars series. Niven himself recommended that Hewitt write one of the stories for the original two MKW books, although this never came to pass.
The magazine Different Worlds, issue 37, featured a Ringworld adventure, "Louis Wu & His Motley Crew." The article "The Dolphins of Known Space: A new race for the Ringworld Game" appeared in Dragon Magazine issue 95.