Logic Masters Deutschland e.V.

Setting with a new constraint to me, parity sight lines. Consensus testing estimate was 2 stars for difficulty, and please be aware of the negative constraint. Good luck!

• Normal sudoku rules apply: Place the digits 1 to 9 once each in every row, column and 3x3 box
• Parity Sight Lines: (see below for an example)
  • A digit in a circle is odd and counts the number of odd digits that can be seen in all orthogonal directions combined, including itself. Even digits block the view
  • A digit in a square is even and counts the number of even digits that can be seen in all orthogonal directions combined, including itself. Odd digits block the view
  • ALL circles and squares are given

Play on Sudokupad

If you are not familiar with sight lines, hopefully this image helps explain:

• The 5 in the circle sees itself, 7 in its row, 9 in its column, and the pair of 1s in its row and column. It does not see any of the 3s as the 3s are either blocked by even digits, or not in the same row/column as the 5
• The 4 in the square sees itself, a 2 and two 6s
• The 1 in the circle sees no other odd digits as the even digits block view, so it only sees itself