It may be hard to imagine that children playing games could have a downside, but many children do experience repercussions from playing with each other and by themselves. As a parent, your best course of action is to discuss safe play with your kids, keep a close eye on them when they're playing and stop any activity that could lead to a dangerous situation immediately.
Breaks from Reality
Allowing your kids to play fairy tale games and play imaginary roles may seem innocent enough in childhood, but it could lead them to have unreasonable expectations about life in adulthood. When real life deviates from the child's fairy tale perspective, like parents divorcing or trouble in relationships, it could lead to emotional issues. Bruno Bettelheim, the author of "The Uses of Enchantment: The Meaning and Importance of Fairy Tales," states that fairy tales and the lack of balance between truth and fantasy could have a negative effect on future generations.
Someone Gets Hurt
One disadvantage of kids playing games is that someone can get hurt, especially in a case where physical activity is involved. Even mild physical play can turn into rough-housing and lead to serious injuries in children. Games like tackle football can cause serious head injuries in children that could lead to problems into adulthood. Sometimes one or more of the children involved in a physical game can get upset or take his physical contact with others too far---since a child doesn't always understand the repercussions of his actions it's very easy for someone to get hurt.
Video Game Related Issues
Parents and educators are concerned about the numerous disadvantages of kids playing video games in particular. For one, video games have a dumbing down effect on some kids---there is little to learn from a game that involves fighting or playing sports. The monotony of watching an animated television screen can also damage the child's eyes over time. The constant use of a controller can cause a repetitive strain injury in a child's thumbs called "Video Gamer's Thumbs." Since a child plays video games while sitting down, he doesn't have chance to experience the outdoors, interact with society, or get exercise to stay fit and healthy. Finally, the violence and mayhem in some video games can desensitize the child and make him more prone to acting out.