Almost everyone, from little children to adults, loves games. The types of games may change and get more complex as we grow up, but our enjoyment never changes. Playing games is both fun and useful, because games teach us the skills we need in life.
First of all, playing games teaches us that everything we do causes something else to happen. If we bit a ball, it will land somewhere or someone will try to catch it. If we make certain combinations with cards, we'll earn points. So when we play a game, we learn there is always cause/effect relationship. We learn to pay attention to what's happening around us and see how people react to what we do.
Playing games also teaches us how to deal with other people. We learn about teamwork, if the game has teams. We learn how to assign tasks according to each person's skill. We learn how to get people to do what we want, and we learn that sometimes we have to do with other people want.
Game playing teaches us how to follow rules to achieve something. In a game, the rules have been worked out in advance and make the game go more smoothly. We find out that if we want to reach a goal, we need to know the rules. We learn how to go step by step towards a desired end. We also learn how to make adjustments when things change. We learn how to devise a plan for reaching our goal. We learn strategy.
Most people understand that "all work and no play" is bad for you. Learning all these things would be much slower if we didn't play games. Life would be much duller, too.