This is the Geary Cube puzzle, another Bram and Oskar collaboration. It's externally identical to a Rubik's Cube, but has internal gearing which forces opposite faces to turn in opposite directions simultaneously. It's my favorite subgroup of the Rubik's Cube (you can try it yourself with a regular Rubik's Cube) and easily makes a bunch of pretty patterns. It's overall easier than a regular Rubik's Cube is, but the solution technique is very different and interesting and not related to the standard ways one solves twisty puzzles.
