Invisible Inkling
(Published on 11. March 2026, 15:35 by Timpanist)
- Normal 6x6 Sudoku rules apply.
- I have drawn all possible white and black Kropki dots into the grid, as well as exactly one thermometer—but I used invisible ink!
- Clues outside the grid indicate the first "invisible" feature seen from that direction (White dot, Black dot, or Thermometer cell).
- White Dots: Border between two cells with consecutive digits.
- Black Dots: Border between two cells with digits in a 1:2 ratio.
- Thermometer: A single path of cells, connected orthogonally or diagonally, where digits strictly increase from one end to the other.
Solution code: Row 2, from left to right
Comments
on 13. March 2026, 14:50 by Timpanist
Lithium-ion, my intention with that line is to indicate that if two cells “could” have a dot between them, then they “must”. Technically, it is a negative constraint, you just can’t see all the dots. I understand how usually that wording on a different puzzle would indicate otherwise.
on 13. March 2026, 12:18 by Lithium-Ion
I really struggled with the wording of the rule "drawn all possible white and black Kropki dots in the grid". I wrongly thought that this would imply a negative constraint on Kropki dots.
on 13. March 2026, 00:09 by pep9
Wonderful puzzle, really cool idea!
on 12. March 2026, 04:46 by Timpanist
Thanks everyone!
on 12. March 2026, 04:13 by juggler
Lovely puzzle!
on 11. March 2026, 16:30 by StefanSch
Interesting ruleset!
