Variant Sudoku 101: Kropki Dots
(Published on 1. December 2025, 01:33 by PhoenixAki)
My Variant Sudoku 101 series introduces common variant sudoku rules, frequently using dynamic fog to help point the solver where to look next. The target audience is those who are comfortable with classic sudoku, but new to variant sudoku. In other words, you are expected to be able to identify things like (but not limited to) pairs and triples in rows/columns/boxes and know how to take advantage of them. I welcome everyone to try this series regardless, just be warned you may have a harder time if you're new to sudoku in general.
- 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.
- 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: Chains of 3 black dots always have both a 2 and a 4 on them because of being either 124 or 248. Pencilmark that in and take note of how that affects what the other black dots in each box can be. Also, pay attention to what the stretch of 3 middle digits around the perimeter must be, and how they interact with the rest of the clues.
Hint 2: White dots must always have 1 even digit and 1 odd digit on them, because that's how consecutive digits work. You can use that to make it easier to figure out where 8 must go in boxes 1 and 9. Then, pay attention to how those white dot chains must go.
Hint 3: Repeat the odd/even trick on the white dots in column 4 and 7, recognizing that there must be a 3 on each dot.
Solution code: Column 5 from top to bottom (9 digits)
Comments
on 17. February 2026, 06:55 by PhoenixAki
"Solving Hints" tag was missing.
on 28. January 2026, 01:26 by PhoenixAki
Added links to Patreon.
on 21. January 2026, 08:36 by PhoenixAki
Added hints after learning recently how to do that in HTML. Wish I knew this a few weeks ago when I went over all my posts...oh well.
on 5. January 2026, 22:11 by PhoenixAki
Updated post as part of an effort to improve consistency of rule phrasing and post layout across all my puzzles.
on 4. January 2026, 19:21 by Prezombie
Decent puzzle for learning basic dot patterns, but repetitive in how the logic is so symmetrical on EVERY LAYER.
on 12. December 2025, 07:40 by PhoenixAki
updated sudokupad link to version that removes redundant fog clearing in a cell. Was put in mostly as a cheeky nod towards the cell but eh.
on 2. December 2025, 09:36 by PhoenixAki
Updated puzzle link: missed updating the title with the previous revision (it no longer says level 1 now). Unfortunately means solve count on sudokupad is lost.
on 2. December 2025, 03:49 by TeddieMilo
Made my day! Tq.
on 1. December 2025, 10:36 by superkinkel
Nice easy one to get people introduced to the concept. Then again, classic Sudoku has a pretty big part for the Kropki focus.
on 1. December 2025, 03:01 by PhoenixAki
updated description to reflect only doing 1 intro puzzle for kropki dots. Next entry in the series will instead be a quiz bringing in killer cage knowledge :)
on 1. December 2025, 02:43 by SennyK
Great kropki dots introduction :-)
on 1. December 2025, 02:28 by Cyprane
That was a lot of fun. Very well designed. Never felt lost or stuck.
