An appropriate consequence might be to separate them for a few minutes. When you must use a punishment, keep it simple and short. Also, remember that an apology is an effective way of teaching. I told him that if he didn't learn to play fair he would never have any friends. I want to console him when he loses.
All children like to win.
Unfortunately, when you play a game that is competitive, there is a winner and one or more losers. If your child wants to participate in this type of game, he must realize that he may lose. A child of six is old enough to understand this basic, albeit difficult, lesson. You can make it a little easier by minimizing the importance of winning and enlarging the importance of fair play and having fun. Once a child learns these foundations, he will be ready for more competitive games.