Redline Alternation
(Published on 11. February 2026, 14:55 by Rab3aron)
Redline Alternation
Rules:
Normal Sudoku: Place digits 1-9 so that each row, column, and 3x3 box contains each digit exactly once.
Parity Line: Along the red line, every pair of consecutive cells on the line must contain one odd digit and one even digit.
Diagonal Sums: Each number outside the grid equals the sum of the digits on the diagonal it is placed on.
Cage Sums: Digits in each cage sum to the number shown in the cage’s top-left corner.
Antiking: Cells separated by a king’s move in chess can't have the same digit.
Antiknight: Cells separated by a knight’s move in chess can't have the same digit.
Happy solving!
Solution code: Enter Row 5 from left to right.
Comments
on 13. February 2026, 12:21 by greemi01
very fun. thanks
on 12. February 2026, 14:34 by Rollo
Ich fand's schwierig.
on 12. February 2026, 11:02 by Rab3aron
Thank you all for the great feedback! Actually I rated this one as 2 starts, but since most people here are very experienced they probably used some advanced tricks to solve it much faster than intended, which led to them giving it a 1 star difficulty.
on 12. February 2026, 08:57 by Martina
Rating this 1* will put off beginners. Please rate realistically.
on 12. February 2026, 01:04 by SanFranSam
I am going to repeat another post. Easy for experts. The colouring was fun. But the blank cells did not make the next step obvious. I guessed right as to which was odd and which was even. If you didn't have to guess i suppose that makes you an expert.
on 11. February 2026, 22:07 by henryng
Gorgeous!!!!
on 11. February 2026, 21:31 by drbs
Very nice and enjoyable.
on 11. February 2026, 19:36 by VitP
definitely not level 1.
"very easy for an expert" does NOT mean the same as "very easy"
on 11. February 2026, 19:31 by Innocuous
This puzzle is being underrated. I realize it's tough for an easier puzzle to get a high rating here, but I found this to be a lot of fun. Very clever construction.
on 11. February 2026, 18:16 by pjot
Thank you, really smooth coloring exercise. Here's a link with solutions checking: https://sudokupad.app/zo0jjnuurx
on 11. February 2026, 18:11 by GeorgeTheToad2
Nice colouring puzzle.
on 11. February 2026, 17:34 by Titus Adduxas
I really enjoyed that. I do like puzzles you can colour in completely and then resolve the digits in a flash.
on 11. February 2026, 16:02 by ketchup_monster
Super fun coloring puzzle! Smooth solve
