That all depends on what time of day you are going. The one by my home in GA has a special going on right now for $15.99- you get an entree and a $10 game card on week days or until 5 pm on weekend days. We get that for the adults in our family and the kids order off the kids menu or share with our daughter (the chicken alfredo type dish is great to split!). Then you can add extra game money to the card to play more games if you want too. It's a great deal and the food is excellent.
It just depends on what you order or play. Depending on the age of the child I would say a 10-20 dollar card per kid for games. I'd say the meals are the same as any other restaurant and there is a kid's menu.