Just take a look at this and you'll see why. My daughters could spend hours on something like this and they'll get smarter for the time spent.
The first, prototype, iteration of the game (not the one seen in the video) is available, for free, at the Kloonigames blog.
Unfortunately, these games are for the PC-enabled set, not us Mac-types.
Oh, and if you like the music from the video, it's "Lullaby" by _ghost and is under CC, so have at it.