Not meant to teach but to revise and coach what was already learned in class, this series of games combine an adventure, logic and strategy puzzles, as well as math drills - there's even a boss mob they have to defeat at the end. The younger kids seem to love them, not so much the 11 year olds - by then they tend to get cocky and arrogant, and decide to hate anything that mom and/or dad recommends.
I reviewed them on http://www.commonsensemedia.org - and the best thing about them? They have an algorithm that tracks how well you (or your kids) do and adjusts the problems so the kids don't get frustrated because they are faced with games they can't possibly win. I was reviewing these with Gary's kids and was thinking... "This is 3rd grade math??" then when I checked his son's game, realized that my questions were quite a bit harder than his.