http://www.sinnesloschen.com/
Spoiler
^ it's a "remake" based on DESCRIPTIONS of the infamous urban legend, so not the "real deal". But that doesn't make it all that much less creepy.*
via http://knowyourmeme.com/memes/polybius and a link from one of the many YouTube videos of [or pretending to be] gameplay of the original game.
* obviously this game (if it ever actually existed!) appeared in a handful of arcades maybe 7 years BEFORE the film "They Live" came out (https://en.wikipedia.org/wiki/Polybius_%28video_game%29) ... but nice touch, programmer!