Looking at a Gear Cube XXL, you can’t help but think about a Rubik’s Cube. Both are 3×3 puzzle cubes with brightly colored pieces. Moreover, both are sold commercially as toys. Created by Oskar van Deventer, the Gear Cube XXL and the smaller Gear Cube are made by Mefferts, a brand of puzzle toys, and are distributed by Recent Toys, Amsterdam, The Netherlands. You also can’t help but notice that Oskar’s cube is different from a Rubik’s. On Oskar’s cube, the pieces have gear tooth shapes on them. This difference goes deeper than the surface. The shapes are actual gear teeth that extend into the puzzle’s interior and that mesh and roll with each other. So, even though it looks like a Rubik’s Cube, Oskar’s cube works quite differently. To understand how Oskar’s cube works, though, you have to start with a Rubik’s Cube. Holding a Rubik’s in your hands, looking at a side, you see nine pieces. The pieces form three columns: a left, a middle, a right. Each column has three pieces. When you work the cube, you turn one column, say the right column, while you hold the left and middle columns steady. With Oskar’s cube, when you turn the right column, the middle column also turns. Now, both columns turn in the same direction, but the middle one turns at half-speed. So, if you do two full turns of the right column, the middle column will do one full turn. Also, because the teeth mesh and rotate, they end up with a different orientation than they had when you started turning the right column. So, you’d have to do many double full turns of the right column to compensate for the turning of the middle column. With all that turning, meshing, and rotating, you may think Oskar’s cube would be hard to solve. “It looks very difficult,” Oskar says, “but it is actually easier to solve because the gears limit how far one can scramble it.” From the start, the gears were the special part, the wrinkle, in the cube’s design. Back then, the cube was a design challenge between friends, an impossible design challenge.