Polybius is a supposed arcade game featured in an Internet urban legend. According to the story, the Tempest-style game was released to the public in 1981, and caused its players to go insane, causing them to suffer from intense stress, horrific nightmares, and even suicidal tendencies. A short time after its release, it supposedly disappeared without a trace. Not much evidence for the existence of such a game has ever been discovered. Polybius gets its name from Polybius, the Greek historian who, among his other works, was known for his works in relation to cryptography and for developing the Polybius square.