Polybius is an urban legend about a rare arcade game that caused seizures or brain aneurysms and was used in mind control experiments to brainwash people and even cause them to kill themselves.
Back in the 1980s, if people wanted to play computer games, they had to go to arcades that had stand-alone machines. The Polybius game was supposedly released in 1981 to arcades in Portland, Oregon.
The machines were completely black and the only decoration was the name 'Polybius' in bright letters at the top. There was just a button and joystick used for gameplay. They say it was a puzzle/shoot-em-up game, somewhat like Tempest, where you move a rotating ship around the screen and shoot to destroy the enemies.
Polybius supposedly became very popular. It was extremely addictive and people would form long lines, waiting to play it. However, there was something sinister as hearing the sound of a woman crying and seeing grotesque faces out of the corner of their eyes. Some saw disturbing subliminal messages flashing up on the screen.
After playing the game, people would have horrible nightmares, waking up in a panic. Others experienced extreme nausea, convulsions and vomiting. Others got headaches, blackouts, hallucinations or even developed amnesia. Some unlucky people even committed suicide.
According to one owner of an arcade, mysterious men in black suits would often come to collect records from the game. They did not collect any money, just data on gameplay and in some cases, they would change the settings. Because of this, the leading theory is that it was some sort of government experiment using subliminal messages to brainwash people and control their minds.
The game remains in obscurity because about one month after the release, all of the cabinets suddenly disappeared. One cabinet reappeared in an arcade 1998, but quickly disappeared again. While some tried to recreate the game, no one has ever found the original ROM. It was supposedly created by a mysterious company called Sinnneslöschen (which is German for "Sense Deletion").