Why are my kids addicted to this series?

My five-year-old is perhaps the biggest Mario fan in the known world and could not wait (or stop bugging me about it) for this game to arrive. Since then I don't believe a day has gone by without him wanting to play it, pretending to play it, or talking about strategies for the mini-games and party modes. This is not the best game for an adult, although it is fun and for a group could be quite enjoyable. But for small children (I can only vouch for 3-9 year olds, but I would say the optimum age group extends quite a bit farther), this game is the right mixture of fun, challenge, and even some exercise (it wears me out playing for extended periods). When my children aren't grounded (which is almost never for the two oldest), they are always playing this game. I would recommend that you have as many controllers as children, due to the tendency of kids to not want to wait for their turn (which in my house leads to fighting - hence the grounding). And if you don't have four kids, make sure you have a controller for Mom and Dad so you aren't left out!