Polybius is an arcade cabinet described in an urban legend, which is said to have induced various psychological effects on players. The story describes players suffering from amnesia, night terrors, and a tendency to stop playing all video games. Around a month after its supposed release in 1981, Polybius is said to have disappeared without a trace. There is no evidence that such a game has ever existed.
The game has shown up in movies & tv shows like The Simpsons and Wreck it Ralph.