Not much evidence for the existence of such a game has ever been discovered. Polybius gets its name from the Greek historian who, among his other works, was known for his works in relation to cryptography and for developing the Polybius square.
According to the story, an unheard-of new arcade game appeared in several suburbs of Portland, Oregon in 1981, something of a rarity at the time. The game proved to be incredibly popular, to the point of addiction, and lines formed around the machines, often resulting in fighting over who played next. This was followed by clusters of visits from men in black. Rather than the usual marketing data collected by company visitors to arcade machines, they collected some unknown data, allegedly testing responses to the psychoactive machines. The players themselves suffered from a series of unpleasant side effects, including amnesia, insomnia, nightmares, night terrors, and even suicide in some versions of the legend. Some players stopped playing video games, while reportedly one became an antigaming activist. The supposed creator of Polybius is Ed Rotberg, and the company named in the urban legend is Sinneslöschen (what seems to be a slightly incorrect German translation for "To have erased your mind"), often named as either a secret government organization or a codename for Atari. The gameplay is said to be similar to Tempest (a shoot 'em up game using vector graphics), while the game is said to contain subliminal messages which would influence the action of anyone playing it.