Polybius was an arcade game that was said to have briefly appeared in several arcades around the Portland, Oregon area during the early 1980s. People who claim to have played the game–or, in most cases, know someone who knows someone who did–say that the machine caused a number of side effects ranging from anxiety and depression to night terrors, suicide, and even sudden death. Some believe Polybius was a product of the CIA’s controversial MK-Ultra program, an experiment in mind control targeting youth. Others believe it may have had extraterrestrial origins. And though the game’s mysteries are vast–theories range from men in black to imported Nazi science, to a recalled Tempest prototype–no one has ever been able to confirm the cabinet’s existence. Many agree it was nothing more than a hoax, perpetrated on internet forums…but even these claims lead to strange and sinister findings.