For example, it was used in the USA as a means of dispute resolution (I have never sounded more QI). A copy of the relevant court order, quoted in Wikipedia, can be found here ...
Upon consideration of the Motion – the latest in a series of Gordian knots that the parties have been unable to untangle without enlisting the assistance of the federal courts – it is ORDERED that said Motion is DENIED. Instead, the Court will fashion a new form of alternative dispute resolution, to wit: at 4:00 P.M. on Friday, June 30, 2006, counsel shall convene at a neutral site agreeable to both parties. If counsel cannot agree on a neutral site, they shall meet on the front steps of the Sam M. Gibbons U.S. Courthouse, 801 North Florida Ave., Tampa, Florida 33602. Each lawyer shall be entitled to be accompanied by one paralegal who shall act as an attendant and witness. At that time and location, counsel shall engage in one (1) game of "rock, paper, scissors." The winner of this engagement shall be entitled to select the location for the 30(b)(6) deposition to be held somewhere in Hillsborough County during the period July 11–12, 2006.A five gesture variant is mentioned in The Big Bang Theory, apparently - "Rock, Paper, Scissors, Lizard, Spock". The existing relationships exist between the first three items, but then defines relationships between Lizard and Spock gestures and each of the other three. Details here. For the game to be balanced, each gesture has to win against half the other gestures and lose against the other half (which means that there should be an odd number of gestures).
But this has been taken even further by someone who went on to create 7, 9, 11, 15, 25 and eventually 101 (!!!!) gesture variants. Yes, you and your opponent can pick any one of 101 gestures, and the winner and loser is defined in each case. You can buy a poster - you'll probably need at least that.
Now, given no multiplayer version exists, is it possible to make one, I wonder?