on a PDP-1 at the Artificial Intelligence Laboratory of Stanford University in 1963; and the University of Minnesota, where MIT graduate Albert Kuhfield in 1967–68 recreated the game for the CDC 3100, and submitted a description to Analog Science Fiction and Fact, published in 1971. The Stanford installation was so popular that in 1966 the researchers created a special "Spacewar mode" for time-sharing computer resources on their PDP-6 so that games could be played on it while research programs were also being run. Early computer scientist Alan Kay noted in 1972 that "the game of Spacewar! blossoms spontaneously wherever there is a graphics display connected to a computer", and Graetz recalled in 1981 that as the game initially spread it could be found on "just about any research computer that had a programmable CRT". The majority of this spread took place several years after the initial development of the game; while there are early anecdotes of players and game variants at a handful of locations, primarily near MIT and Stanford, it was only after 1967 that computers hooked up to monitors or terminals capable of playing Spacewar! began to proliferate, allowing the game to reach a wider audience and influence later video game designers—by 1971, it is estimated that there were over 1000 computers with monitors, rather than a few dozen. It is around this time that the majority of the game variants were created for various computer systems, such as later PDP systems, and in 1972 the game was well known enough in the programming community that Rolling Stone sponsored the "Intergalactic Spacewar! Olympics". The event was held on October 19, 1972, at the Stanford Artificial Intelligence Laboratory using a variant of Spacewar! on a combined PDP-6/PDP-10 that supported five players, and was the first ever video game tournament, with an account published in the December 7, 1972 issue of Rolling Stone. In the early 1970s, Spacewar! migrated from large computer systems to a commercial setting as it formed the basis for the first two coin-operated video games. While playing Spacewar! at Stanford sometime between 1966 and 1969, college student Hugh Tuck remarked that a coin-operated version of the game would be very successful. While the high price of a minicomputer prevented such a game from being feasible then, in 1971 Tuck and Bill Pitts created a prototype coin-operated computer game, Galaxy Game, with a PDP-11, though they never