Overall, Gamestar Mechanic is one of the best-documented and approachable game-design tools available to kids and their teachers. It partners with a number of major players in the emerging Connected Learning movement (such as the MacArthur Foundation and the Mozilla Open Badges Initiative), and its blog routinely shares useful game-based learning resources.
Kids learn in creative ways and are encouraged to be creative themselves. For example, they can customize games with their own artwork. Directions are clear and easy to follow; creations are real and playable. Kids have to think both mathematically and creatively to build games. Also, learning goes outside the classroom, as accounts are non-transferrable but kids can access them from home.