[This is a repost from our archives with new notes at the top (original post here): Greater than/less than constraints can lead to good forcing chains in different number puzzles. However, I’ve never been a fan of using lots of < and > shapes (particularly when rotated 90 degrees) as that notation only works well across pairs of cells and not across chains of connected cells. I created Thermo-Sudoku as a new presentation method to make multi-cell constraints more easily seen and allow for graphically interesting themes. I first developed the style and name while planning for the book Mutant Sudoku with Wei-Hwa Huang, with imagery of a “melted thermometer in the boiling sudoku solution being poured out on paper” as the first mutation caused by Dr. Sudoku’s mistakes in the lab.]

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Grandmaster Puzzles (the G and P shapes in the corners)

Rules: Standard Thermo-Sudoku rules. Range is 1-6.

Estimated Difficulty*: 1 star

Time Standards (highlight to view): Grandmaster = 0:40, Master = 1:00, Expert = 2:00

Solution: PDF

Note: Follow this link for more Thermo-Sudoku puzzles. If you are new to this puzzle type, here are our easiest Thermo-Sudoku to get started on. More Thermo-Sudoku puzzles can be found in The Art of Sudoku 2 and in Masterpiece Sudoku Mix 2.