Normal Sudoku rules apply. Each coloured region is a killer cage i.e. the number given in the top left is the sum of the digits in the killer cage. Digits do not repeat in a killer cage.
Additionally, each killer cage could act as a thermometer, that is there is a path within each cage that is strictly increasing. For example, a cage of three with 1-3-9 is valid, but 1-9-3 is not. In the case of 2x2 boxes, this picture illustrates the rules.
This is part of a group of "Thermal Killer" sudokus. There are 3 different puzzles, and a bonus puzzle which requires the solutions of the 3 puzzles. This was inspired by Eggr's Hidden Clone series
This is, in my opinion, the hardest of the three thermal killer sudokus.
Solution code: Row 4, followed by Column 6
on 18. May 2020, 10:49 by Madmahogany
The bonus puzzle has been uploaded
on 17. May 2020, 21:01 by Madmahogany
Further corrections
on 16. May 2020, 23:27 by Madmahogany
Updated links
on 16. May 2020, 23:22 by Madmahogany
Change in rules
on 16. May 2020, 23:21 by Puzzle_Maestro
In general, I would recommend releasing these puzzles one a day, not all at the same time. This way solvers are given more time to each one individually.
on 16. May 2020, 23:20 by Madmahogany
Change in the puzzle