Normal Sudoku rules apply. An arrow outside the puzzle indicates that the X-Sum, Sandwich, Skyscrapers, and Little Killer clues at that location are identical. Cells joined by a white dot contain consecutive values. Cells joined by a black dot contain values where one is double the other. Not all dots are given.
- X-Sum - the sum of the first X cells in the row or column from that direction, where X is the first number in the row or column.
- Sandwich - the sum of digits between the 1 and 9 in that row or column.
- Skyscrapers - the numbers within the grid represent the heights of skyscrapers. Clues outside the grid indicate the number of visible skyscrapers in that row or column as seen from that vantage point.
- Little Killer - the sum of digits along the indicated diagonal. Digits may repeat along a diagonal.
Penpa+
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