There are presently four games. Here is a screenshot of the Scrambled Tree game:
This game could be a real challenge to someone who was not well acquainted with their first five generations of ancestors. I think this is what has been missing from genealogy. I realize there are other game websites out there, but most have taken the physical board game or trivia pursuit type of approach. For a sample of other "fun" projects, see Family History Activities for Children: 3-11.
Here are some additional links that might be of interest: