Draw a closed loop into the grid, that travels horizontally, vertically and diagonally and passes through each cell exactly once. The loop may cross itself. The numbers indicate what kind of turn the loop makes in the respective cells: a clue number times 45° gives the angle formed by the loop, see figures below (rotations are possible).
(Rules and example from WPC 2019 IB)
History of the puzzle
Invented by Axel de Feijter (Netherlands) in 2012. First appeared on LMD portal. "Achtelwenden" loosely means "one-eighth turn" in German.
Appearances in the past WPCs
- WPC 2019/Round 2 by Christian Halberstadt