1) Normal Sudoku rules apply.
2) Digits along thermometers must strictly increase from the bulb end.
3) NEGATIVE CONSTRAINT: ALL POSSIBLE orthogonally connected thermometers of length 4 are given. That is, other than the given thermometers, there is no non-branching orthogonally connected path of length 4 or more where the digits strictly increase. See the 4x4 example below for an example of the negative constraint.
You can play it here: f-puzzles. Or here: CTC-App. Good Luck!
You can play the example here:f-puzzles
Note that the incorrect solution on the left violates the negative constraint. Both the blue region and the red region contain an orthogonally connected path of 4 cells which strictly increases. So the red cells violate the negative constraint, and the blue cells violate the negative constraint. (There are other violations as well).
Solution code: Row 2 + Row 8 (18 digits. NOT from the 4x4 puzzle)
on 8. January 2022, 23:00 by Siebuhh
I really liked this new negative constraint, it is even stronger than I thought. Very nice puzzle!