Standard Sudoku rules are in effect, i.e., each row, column, and 3x3 box must contain one each of the digits 1-9.
The reddish kitty on the left is made of two German Whispers lines. Each successive pair of digits on a line must be at least 5 apart, e.g., 7161938294916 or 839.
The hazy grey kitty on the right (red kitty's Astral Projection :tm: ) is made of two palindrome lines. They read the same backward as forward, e.g., 34655643 or 121.
The circled digits are quadruples, meaning that the four cells surrounding the circle must contain the given digit or digits, albeit in any order or position (these digits may also repeat as long as they don't contravene sudoku rules or prohibit the placement of other required digits in the quadruple.
Solution code: The 1st row, followed by the 8th column (18 digits total)
on 27. July 2021, 11:44 by ffricke
Die Katze zeigte nur ganz kurz ihre Krallen, dann ließ sie sich durch achtsames Folgen des Lösungswegs besänftigen. Sehr schön.
on 13. July 2021, 11:14 by Mody
Tolles Design und wunderschön zu lösen
on 3. May 2021, 03:54 by cristophermoore
Wonderful! I loved how long it took to figure out which cells on the German whisper were high or low. And, of course, because cats.
on 23. March 2021, 04:18 by Orpheus
Wow!! What an amazing journey! Just spectacular!
on 21. March 2021, 17:24 by pdabraham
Absolutely loved it. Lovely puzzle.
on 20. March 2021, 00:42 by cam
Gorgeous puzzle! Thanks :)
on 18. March 2021, 02:55 by TotallyNormalCat
Cute cat :3
on 17. March 2021, 17:55 by abed hawila
The interaction between all the clues is perfect. Very nice!
on 17. March 2021, 17:51 by Boondiggle
A very cute puzzle, and fun to solve too!
on 17. March 2021, 17:30 by PseudoCoup
This puzzle is a gem!
on 17. March 2021, 06:34 by cdwg2000
Very nice!