Try your luck against the computer. This game is based on the Japanese 'game' of jan-ken, which basically works the same as paper-scissors-rock: paper beats rock, rock beats scissors, scissors beats paper. Simple as that (but there's more explanation below, for those who are interested).
Just click on the rock, paper or scissors image to make your first choice and start the game. Keep going till you can't take any more!
Japanese people, young and old alike, use jan-ken to decide things, in much the same way that western people flip a coin. Being a three-way rather than a two-way process makes it more efficient and of course no props are needed.
As a game between two people, it has another level - the initial winner says 'atchi mite hoi! (look there!)' and points up, down, left or right. If the other person looks in the same direction, they lose.
It's more difficult than it seems. But jan-ken is so popular and widespread among Japanese that they can play it remarkably fast. It can even be played for money by many people at a time, with people being paired off in each round and the winner keeping the loser's stake.