Philosophers spend a lot of time grappling with tangles, and trying to come up with clear pictures.  Mental cross-training is important.  So little of what we do is purely deductive, that exercises like sudoku can’t give us the workout we need.  So little of what we do is merely verbal, that crosswords don’t cut to the quick.  And none of us is getting any younger (the lives some of us have led–how can we take comfort in the Nun Study?).  Enter Planarity.  Make it to level eight, and Hegel shucks like an oyster.  Also good training for dealing with iPod wires, and easier than Rubik’s Cube (now 25 years old).