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Theme: Tic-Tac-Toe

Author/Opus: This is the 7th puzzle from guest contributor Zoltán Horváth.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 3rd row from left to right, followed by a comma, followed by the 7th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 4:15, Master = 6:45, Expert = 13:30

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.

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Theme: Spiral

Author/Opus: This is the 269th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 5th row from left to right, followed by a comma, followed by the 7th row from left to right.

Time Standards (highlight to view): Grandmaster = 4:45, Master = 6:00, Expert = 12:00

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.

Here are our best Sudoku puzzles of 2018, selected from the 42 web posts in this category:

Visually distinctive puzzles were an important part of the top Sudoku from 2018. While posted in our last week of 2018, this Christmas Tree Sudoku by Thomas Snyder (that combines Sudoku with the popular Star Battle style) got a lot of FAVE votes in a rather short time.

While we have been avoiding “Pi” puzzles for a long time here — some of us assert there is a more fundamental mathematical constant around 6.283 — having some new editors involved on the web led to our first full week of “Pi” puzzles in March and some others later in the year. Two Pi sudoku stood out including this Consecutive Sudoku from guest contributor Fatih Kamer Anda.

Another prize goes out to an Arrow Sudoku from Murat Can Tonta.

The best sudoku of 2018 goes to another Pi-themed puzzle, a Thermo-Sudoku by Serkan Yürekli with an incredibly elegant arrangement of its givens that still leads to a fundamentally interesting logical solve.

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Theme: Clueless

Author/Opus: This is the 6th puzzle from guest contributor Ashish Kumar.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 5th row from left to right, followed by a comma, followed by the 7th row from left to right.

Time Standards (highlight to view): Grandmaster = 7:00, Master = 13:30, Expert = 27:00

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.

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

Theme: Sun

Author/Opus: This is the 2nd puzzle from guest contributor Kishore Kumar Sridharan.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 1st column from top to bottom, followed by a comma, followed by the 4th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 5:00, Master = 7:30, Expert = 15:00

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.

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

Theme: Candlepower

Author/Opus: This is the 53rd puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 5:30, Master = 11:00, Expert = 22:00

Solution: PDF; a solution video is also available here.

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.

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

Theme: Pi Circle in Order

Author/Opus: This is the 182nd puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 4th row from left to right.

Time Standards (highlight to view): Grandmaster = 4:00, Master = 5:00, Expert = 10:00

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.

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

Theme: Diamonds (for Chris Green)

Author/Opus: This is the 150th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Classic Sudoku Rules. Also, some arrow shapes are in the grid; the sum of the digits along the path of each arrow must equal the digit in the circled cell. Some thermometer shapes are in the grid; digits must be strictly increasing from the round bulb to each flat end. Finally, some diamond shapes are in the grid; the labeled diamonds below the grid must be placed in some order onto the shapes in the grid. The labeled diamonds can be rotated but cannot be reflected.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 5:15, Master = 10:45, Expert = 21:30

Solution: PDF

Note: Follow this link for other less common variations of Sudoku and this link for classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More Arrow and Thermo-Sudoku puzzles can be found in The Art of Sudoku 2.

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Theme: X-Box

Author/Opus: This is the 8th puzzle from guest contributor Swaroop Guggilam.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 8th row from left to right.

Time Standards (highlight to view): Grandmaster = 6:30, Master = 13:00, Expert = 26:00

Solution: PDF; a solution video is available here.

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.

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

Theme: Weightlifter

Author/Opus: This is the 115th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Thermo-Sudoku rules.

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 6th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 5:30, Master = 8:30, Expert = 17:00

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.