https://en.wikipedia.org/wiki/Polybius_(video_game)
Polybius is an urban legend surrounding an arcade game that supposedly had a limited run in select northwestern arcades during the early 80s. The game’s existence has been hinted at in video game message boards and websites since the early 2000s, but no reliable physical evidence has ever been provided by those claiming to own it.
The story goes that in 1981 Polybius was created by a fringe government research group, as a method to test the potential for videogames to stimulate and influence the player’s mind. After claims that those who played Polybius suffered from amnesia, night terrors, and hallucinations, the game suddenly disappeared from all arcades in a massive cover-up.
The gameplay itself is also shrouded in mystery, but a few second hand accounts describe Polybius as a space shooter with puzzle-like elements. The sensory experience is often described as psychedelic, composed mainly of vector graphics of colorful shapes, and with a soundtrack of loud dissonant synthesizers.
