Check Yourself
(Eingestellt am 10. Januar 2026, 07:18 Uhr von PhoenixAki)
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The original concept for this puzzle was a vague idea of wanting to force a specific bit of knowledge about German whisper lines, and it wound up becoming my first path puzzle, and my first puzzle that I + other testers estimate to be 3/5 star difficulty. This took a few nights of banging my head against the wall to get it to work right, but I'm quite happy with the result. Big thanks to both TVDK and sujoyku for helping with testing and some development of the idea.
Rules:
To increase accessibility to my puzzles, I include hints in my puzzle posts (see below). I also post solution videos on my Patreon and YouTube channel. Puzzles released prior to February 2026, as well as my snackdoku and variant sudoku 101 series will continue to get public solution videos on YouTube, while others will be Patreon-exclusive.
Hint 1: Knowing that R1C1 is on the path means it can't have a 5 on it and must be either a high or low number. You can work out which it must be using the clues in R1 and C1.
Hint 2: Once you know the polarity of R1C1, you have to be aware of the "bishop's rule", or as I call it, the "chckerboard rule" (which is what the title refers to). The solution video explains it in more detail, but I've included an attempt to explain it in text here. It is relevant because there is only one "line" in the puzzle (the path) and it only moves orthogonally. Knowing that R1C1 must be high means that any other cell that is on the path and also on the same diagonal (and every other diagonal away from it) must also be high. Test it out by drawing example paths in the grid and you'll see that the low/high pattern will always correspond to every other diagonal.
Hint 3: Once you recognize the pattern in hint 2, you can deduce that R4C4 must be high, and in turn you can prove the cage must be a 127 cage. This results in an interesting pattern of 12 pairs around the center of the puzzle which interacts with the 5 cages. Pay special attention to which "type" of 5 cage each one can be (14 or 23) and see if you can then work out what R1C8 must be.
Hint 4: Once the break-in fog clears and you can see R9C7, you will not get any new fog clearing of new clues until the path is fully filled in with digits. For the most part, this just takes classic sudoku skills while also factoring in the rules about how the path can move. Look ahead a step or two on the path at all times to find sub-paths that would break the puzzle. To fully fill the path, it helps a lot to do non-path coloring. This means using the bishop's rule again but to color any cell that definitely is *not* on the path as a different color, so you can visualize where are the ways the path could go in the grid. This strategy allows you to prove someting about R2C4 at a certain point.
The original concept for this puzzle was a vague idea of wanting to force a specific bit of knowledge about German whisper lines, and it wound up becoming my first path puzzle, and my first puzzle that I + other testers estimate to be 3/5 star difficulty. This took a few nights of banging my head against the wall to get it to work right, but I'm quite happy with the result. Big thanks to both TVDK and sujoyku for helping with testing and some development of the idea.
- Normal sudoku rules apply. Place the digits 1-9 in each row, column, and 3x3 box without repetition.
- Dynamic Fog: The grid is partially covered in grey fog. Placing correct digits will clear the fog, at minimum under that cell and sometimes in other parts of the grid. No guessing is required.
- Whisper Path: Draw a path through the grid which starts and ends with the cells with stars (R1C1 and R9C8). The path acts as a German whisper line, in which adjacent digits must have a difference of at least 5. Cells with green circles are given as part of the path. The path may only move orthogonally and can not touch itself, even diagonally.
- Killer Cages: Digits in dotted-line cages must sum to the number in the top left corner of the cage. Digits may not repeat within a cage.
- Kropki Pairs: Digits separated by a black dot must have one digit be double the other (a 2:1 ratio). Digits separated by a white dot must be consecutive.
To increase accessibility to my puzzles, I include hints in my puzzle posts (see below). I also post solution videos on my Patreon and YouTube channel. Puzzles released prior to February 2026, as well as my snackdoku and variant sudoku 101 series will continue to get public solution videos on YouTube, while others will be Patreon-exclusive.
Hint 1: Knowing that R1C1 is on the path means it can't have a 5 on it and must be either a high or low number. You can work out which it must be using the clues in R1 and C1.
Hint 2: Once you know the polarity of R1C1, you have to be aware of the "bishop's rule", or as I call it, the "chckerboard rule" (which is what the title refers to). The solution video explains it in more detail, but I've included an attempt to explain it in text here. It is relevant because there is only one "line" in the puzzle (the path) and it only moves orthogonally. Knowing that R1C1 must be high means that any other cell that is on the path and also on the same diagonal (and every other diagonal away from it) must also be high. Test it out by drawing example paths in the grid and you'll see that the low/high pattern will always correspond to every other diagonal.
Hint 3: Once you recognize the pattern in hint 2, you can deduce that R4C4 must be high, and in turn you can prove the cage must be a 127 cage. This results in an interesting pattern of 12 pairs around the center of the puzzle which interacts with the 5 cages. Pay special attention to which "type" of 5 cage each one can be (14 or 23) and see if you can then work out what R1C8 must be.
Hint 4: Once the break-in fog clears and you can see R9C7, you will not get any new fog clearing of new clues until the path is fully filled in with digits. For the most part, this just takes classic sudoku skills while also factoring in the rules about how the path can move. Look ahead a step or two on the path at all times to find sub-paths that would break the puzzle. To fully fill the path, it helps a lot to do non-path coloring. This means using the bishop's rule again but to color any cell that definitely is *not* on the path as a different color, so you can visualize where are the ways the path could go in the grid. This strategy allows you to prove someting about R2C4 at a certain point.
Lösungscode: Row 3 from left to right (9 digits)
Zuletzt geändert am 17. Februar 2026, 06:56 Uhr
Gelöst von TVDK, mayiyang, AllesUgo, Fizz, RoystonDA, Joven, JoeyJoeJoe, MissAmy254, sujoyku, Oddlyeven, RobJH, Snookerfan, Piff, lutzreimer, mellowrobinson, Prince Joffrey, sedici, gdc, SKORP17, Hizuriya, ... emie, tim_vermeulen, QuiltyAsCharged, scushuaishuai, DedaKosta, lmdemasi, Pfanni, Kino, Dester, VolpeRosso, MattJones, schnitzl, OGRussHood, Uhu, RadchenkoAleksandr, CareBaer, Lor, tifuuu, jimblek
Kommentare
am 17. Februar 2026, 06:56 Uhr von PhoenixAki
"Solving Hints" tag was missing.
am 28. Januar 2026, 01:27 Uhr von PhoenixAki
Added links to Patreon.
am 14. Januar 2026, 12:06 Uhr von PhoenixAki
Added hints after learning recently how to do that in HTML. Wish I knew this last week when I went over all my posts...oh well.
am 11. Januar 2026, 01:47 Uhr von Exigus
Very nice path-building. Nice and smooth. Thanks!
am 10. Januar 2026, 18:14 Uhr von Franjo
Thank you very much for creating and sharing this beautiful foggy path-puzzle.
am 10. Januar 2026, 15:47 Uhr von Snookerfan
Fun puzzle, thanks!
am 10. Januar 2026, 13:35 Uhr von Oddlyeven
Very enjoyable, thanks!
am 10. Januar 2026, 12:43 Uhr von sujoyku
Thank you for this lovely puzzle, PhoenixAki! Full of nice path logic and interesting interactions, just a blast to solve.
am 10. Januar 2026, 12:10 Uhr von MissAmy254
Really enjoyed this one!
am 10. Januar 2026, 12:00 Uhr von JoeyJoeJoe
01:35:56 for me - thanks for setting
am 10. Januar 2026, 10:52 Uhr von Fizz
That was a very fun puzzle, thanks!
