Logic Masters Deutschland e.V.

Normal Sudoku rules apply.

Yin Yang

Shade some cells in the grid so that all shaded cells are orthogonally connected, and all unshaded cells are orthogonally connected. No 2x2 region may be entirely shaded or entirely unshaded. One end of each line is shaded and the other end is unshaded. The cells containing given digits are all shaded.

Key cells

Each line has a cell which is shaded differently from the other two cells. This is the key cell for the line. Key cells may not be orthogonally adjacent. A digit in a key cell counts how many times that digit appears in a key cell. If a line's key cell is shaded its value is the difference between the values of the other two (unshaded) cells. If the line's key cell is unshaded, its value is the sum of the other two cells.

Unshaded Fortress

Unshaded cells which are not on lines are fortress cells - the value in a fortress cell is greater than the value in any orthogonally adjacent shaded cell.

Modified fortress: the given digits have value zero. All other cells have value equal to the digit they contain.

This was an entry to turn 1 of the 2024 Skunkworks league. Look out for other puzzles with TSL in the title – there were some brilliant creations.

Here is the SudokuPad link: Unruly lines