Logic Masters Deutschland e.V.

Normal sudoku rules apply: each digit, 1-9, appears exactly once in each row, column, and 3x3 box.

Killer cages: in cages, digits cannot repeat and sum to the number in the top-left corner.

Skyscraper: digits placed outside the 9x9 grid are skyscraper clues. Each digit within the 9x9 grid represents the height of a building in its cell. Taller buildings obstruct the view of shorter ones behind them. Cells outside the grid must contain the digit equal to the number of buildings visible from that vantage point in the adjacent row or column.

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