This is probably the first truly worthy thing I put together in Flash. (Yes, it took nearly two years.) In any case, it’s traditional rock, paper, scissors. If you don’t know the rules, look them up. If you look them up and still don’t understand how the game works, then please, back away from the computer and wait quietly for help.
It’s a little on the slow side and could use an update. Maybe 16-player co-op multiplayer with achievements. Til then, try and beat the computer. First to score 10 points wins. Good luck.