Logic Masters Deutschland e.V.

• Normal sudoku rules apply: Place the digits 1-9 once each in every row, column, and 3x3 box.
• Tentropic Doppel-Dög loop: Draw an orthogonally connected loop through the centers of some cells that does not touch itself, even diagonally.
• The loop starts from the cells marked with the dog and the arrow and is considered to be oriented in the direction indicated by the arrow.
• A cell on the loop with a digit D has a value equal to the digit in the cell D steps away along the loop in the orientation given by the arrow. The values of cells not on the loop are the digits they contain.
• Every set of 4 adjacent digits (not values) on the loop must contain a digit from each of the X-pair (ten-pair) subsets of {1,9}, {2,8}, {3,7}, and {4,6}. A 5 may not appear on the loop.
• Killer: Values in a cage sum to the indicated total. Digits may not repeat within a cage, but values may.
• Quads: Values in a circle must appear in the surrounding 4 cells, at least as many times as they are shown in the circle.

Solve in SudokuPad