Show HN: Play rock-paper-scissors against your computer via webcam, neural nets
Which reminds me... I saw a funny trick once. Probably impossible through network, but there was an implementation that would always win, no matter what you'd choose. The secret was, image recognition was instantaneous and showed winning hand on the screen so fast that human assumed it is fair play. At the beginning you'd thought they are lucky. After few games - they have a good prediction algo. But after some time you feel weird. Of course people guessed sooner or later, but it was funny anyway.