Normal sudoku rules apply.
Any two cells separated by a knight's move (in chess) cannot contain the same digit.
Digits on thermos must increase from the bulb.
Additionally, cells a knight's move away from a thermo bulb cannot contain any of the digits on that thermo. (see example below)
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Bless you!
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Example
Thermo A and B is correct and can see each other even tho both have an 3 and 4 in common, as neither 3 or 4 is in the bulb
Thermo D would be able to see thermo C bulb, but thermo C bulb can not see thermo D bulb, as the 4 in thermo C will see the 4 in thermo D with knight's move
Solution code: give the digits of column 4 (top to bottom)
on 7. January 2026, 12:41 by Exigus
Great coloring exercise but very challenging. Thanks!
on 7. January 2026, 12:20 by BG03
Took me ~4 hours to grind through this puzzle. 4* difficulty felt correct - it was a lot of goodliffing and very easy to make mistakes...
(Spoiler)
Colouring helps a lot!