Red + Blue = Purple
(Published on 21. July 2025, 17:54 by Kaktuslav)
Rules: Normal Sudoku rules apply. Yin-Yang: Color each cell in the grid either red or blue, such that no 2×2 square is monochromatic and the cells of each color form a single orthogonally connected region. Lines:
- Every line that passes through at least one red cell is an alternating-parity line (i.e. each pair of consecutive digits along the line must include one even and one odd digit).
- Every line that passes through at least one blue cell is a region-sum line (i.e. box borders divide the line into segments with equal sums; these sums may vary between lines).
- Any line that passes through both red and blue cells is also a renban (i.e. it contains a set of consecutive, non-repeating digits in any order).
If you enjoyed this puzzle, you might like a different (and slightly more difficult) take on `lines of unknown nature' here :)
Solution code: All the blue digits in row 5 (left to right) followed by all the red digits in column 5 (top to bottom)
Comments
on 27. July 2025, 12:47 by polcat
Incredible puzzle - loved it. Thanks!
on 26. July 2025, 15:04 by oskode
Really smooth solve with fun logic all the way through, thank you!
on 26. July 2025, 00:06 by Allagem
Some very original logic in this one, with an ending that played out quite differently than what I was expecting. Enjoyed it a lot!
on 22. July 2025, 13:15 by 9Rookienumbers
Brilliant take on YY, thanks!
on 22. July 2025, 01:26 by zeniko
Parities are red
Region-sum blue
Renban are both
Thanks to you!
on 21. July 2025, 20:13 by thoughtbyte
Excellent puzzle, lots of fresh, interesting logic packed in a nice, smooth flow. Well done, thanks!
