I've always been interested in Polybius.
Supposedly, it was this arcade game that appeared in 2-3 locations in Oregon during the early 80's. The game itself was something like a psychedelic puzzler kind of thing.
As the story goes, kids got
scary addicted to it, and most of the people that played it started experiencing all kinds of night terrors, hallucinations, amnesia, suicide...you name it. Your typical "men in black" would show up daily and collect data from the machines, which led people to believe it was some kind of government experiment.
It's all rumor and speculation, and there is
nothing resembling evidence in any way, shape or form...but as far as urban legends and conspiracy theories go, I've always found it cool.
http://www.coinop.org/g.aspx/103223/Polybius.html