This took me down the rabbit-hole of the author's website, mindsports.nl, which has a number of interesting problems in puzzles and games. I was particularly piqued by the China Labyrinth and related family of puzzles:
http://www.mindsports.nl/index.php/puzzles/tilings/china-lab...
It will be more difficult to sleep now that I know nobody has answered the question: "Why do both known 16x16 solutions to the Octopuszle feature the same diagonal complex?"