Limit video game time. Two hours a day or less is a reasonable limit. Or allow an hour of play on school nights and 2 or 3 hours a day on weekends. Some parents allow the video games only on weekends. If your child is doing poorly in school, temporarily eliminate video game time on school nights.
Some parents allow their children to earn video game time by putting in equivalent reading time.
Don't allow your child to postpone bedtime because he wants to finish a video game. Remember that children who stay up late are usually too tired the next day to remember what they are taught in school. Don't allow your child to have a video game set in his bedroom, because this eliminates your control over time spent playing. When bedtime is drawing near, give your child a 10-minute warning. Encourage your children to settle their own disputes over using the video game.