Polybius

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.

Story
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 (German for "sensory-extinguishing" is the exact translation), 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.

Origin
The origin of the legend is unknown. Some internet commentators think it originated as a usenet hoax. Other bloggers believe the story is a true urban legend – one that grew out of exaggerated and distorted tales of an early release version of Tempest that caused problems with photosensitive epilepsy, motion sickness and vertigo; the early release of the game was therefore pulled.

PC game
On July 20, 2007 a Sinneslöschen website went online, offering a freeware Polybius game for download, as well as artwork for the cabinet. The game, created with DarkBASIC, features gameplay and graphics based on the interview with Steven Roach and includes messages with the same text as those in the 1988 movie They Live. This and the site were made by the same person who created and released other freeware games at the site RogueSynapse. In fact, both sinnesloschen.com and roguesynapse.com point at the same IP address, while the PC Polybius game can be seen running in a custom cabinet in a photograph at RogueSynapse.

Several videos of this game have been made and uploaded to YouTube, where it is often described as if it were the actual game the urban legend is about. Some videos, due to their spinning graphics, may have negative effects to those with epilepsy.