DragonBox Elements from WeWantToKnow teaches players the fundamentals of geometry -- shapes, theorems, even proofs -- without ever letting on that it is a learning app. A ship of Viking-like characters arrives at the base of a tower to battle the monster Osgood, and players have to solve geometric puzzles to collect little creatures to fight.

The creatures are based on the shapes that hide them -- triangles (scalene, isosceles, equilateral) and quadrilaterals (irregular, rectangles, squares, rhombuses, trapezoids, and parallelograms), linked by complex networks of line segments and circles. Players must follow increasingly advanced logical progressions in order to reach the goal of each level. All the terminology is hidden from the players, however; those who wish to learn a little more can consult the book of knowledge available in the game, and parents and teachers can take this further by integrating the game into the curriculum plan provided on the WeWantToKnow website. Those players who merely play the game as a discovery experience will learn every bit as much; when they finally encounter geometry concepts in school, it has the potential be familiar and fun.

Because the educational side of the game is downplayed, players never feel that the game is work. Our 9-year-old hated to put the game down, exclaiming, "Oh!" or, "Cool!" every time she gained a new "power" (what the app calls the new types of shapes and new ways of connecting them) or discovered a connection that had eluded her. Even grown-ups enjoyed playing, though this is a game better left for children to discover with less guidance, so they can make the logical leaps independently. With 110 levels, there are hours of play (and a lifetime of learning) to be had.