This is my favorite game/toy for Landon yet. First of all, it's beautiful. With a wooden board and colored wooden marbles, it is gorgeous to see him playing it. Basically it's Suduko for kids. You have to have one of each color (and not more than that) in each row, column, and 9-square grouping.
It's thought provoking and good for him to do mostly on his own. I highly recommend it. It comes with a stack of picture cards which show you how to set the board up, and they range from easy to challenging. We have only done the first 5 and are enjoying the quality time working on it, but Landon insists on doing it mostly on his own.