Logic Masters Deutschland e.V.

This puzzle was set for Round 2 of the Puzzle Agency Championship, in which participants were challenged to make a puzzle incorporating two 3x3 clones given at the outset.

I shamelessly stole, ahem, “borrowed” the Yin-Yang U-Bahn ruleset from Christounet, who created it for his outstanding Secret Satan gift for Piatato last year. This combination struck me as the perfect foundation to weave in the clone-based logic.

The solver should be aware that difficulty opinions during testing and judging varied considerably; YMMV depending on your familiarity with the ruleset elements.

• Yin Yang: Shade some cells such that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and no 2x2 area is fully shaded or fully unshaded. (Note: as shaded/unshaded are completely arbitrary in this puzzle, you may assign R1C1 as "unshaded")


• U-Bahn: Draw a totally connected loop network through the centers of some cells, which may branch or turn, but may not have any dead ends.


• Clones: The 3x3 dashed cages are clones. Cells in the same relative position within the clones must have the same shading and line shape/orientation.


• Interaction: For each row/column, a set of clues outside the grid corresponds to either shaded cells only, or unshaded cells only (the solver must determine which). A clue indicates how many times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the corresponding row or column, irrespective of the line shape's rotation.


• Additionally, for rows or columns that include the same relative positions of clones, sets of clues must correspond to the opposite shading. For example, if Row 2 clues correspond to shaded cells, then Row 6 clues must correspond to unshaded cells, because they both “see” the top row within the 3x3 clone. (The same relationships apply for R3/R7, R4/R8, C2/C6, C3/C7, and C4C8)