This year, we have started to have some extra difficult Sunday Stumpers, about once a month. These will be quite tough puzzles, but with a logical path to be found (and solution videos to help). This second Sunday Stumper is a challenging Sudoku variation with a special theme for Pi Day, whether you like Pi or are in the Anti-Pi = Tau camp.

PDF

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

Theme: Pinenut

Author/Opus: This is the 320th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Sudoku rules. Also, no two of 3, 1, and 4 can appear in adjacent cells. Some cages are marked by dashed lines; the sum of the digits in each cage must equal the value given in the upper-left corner of that cage (digits cannot repeat inside a cage). Some arrows given outside the grid indicate the sum of the digits along that diagonal path (digits can repeat on a diagonal). The value of any ungiven sum in either a cage or an arrow must not be a number composed solely of the digits 3, 1, and 4 (like 4, 11, 14, 31).

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 28:00, Master = 1:00:00, Expert = 2:00:00

Solution: PDF; a solution video is also available here from Dr. Sudoku and another video here from Cracking the Cryptic.

Note: Follow this link for other variations on Sudoku.

PDF

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

Theme: Waves

Author/Opus: This is the 59th puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Standard Sudoku rules.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:30, Master = 8:30, Expert = 17:00

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

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: Double S

Author/Opus: This is the 1st puzzle from guest contributor R. Kumaresan.

Rules: Standard Sudoku rules.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 3:00, Master = 6:45, Expert = 13:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: Turnstile

Author/Opus: This is the 9th puzzle from guest contributor Rajesh Kumar.

Rules: Standard Sudoku rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:30, Master = 3:30, Expert = 7:00

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

This year, we are going to have some extra difficult Sunday Stumpers, about once a month. These will be quite tough puzzles, but with a logical path to be found (and solution videos to help). This first Sunday Stumper is a challenging Sudoku variation in the style of some of the unusual rule mash-ups and difficulty seen on the Cracking the Cryptic channel.

PDF

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

Theme: Have a Cracking New Year!

Author/Opus: This is the 371st puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules. 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 (digits can repeat on an arrow). Some thermometer shapes are in the grid; the digits along the thermometer must be strictly increasing from the round bulb to the flat end. Some rectangular cages are in the grid marked by dashed lines; the sum or product of the digits in these cages must be either 20 or 21. Finally, some arrows are given outside the grid; the sum or product of the digits along these marked diagonals must be either 20 or 21 (digits can repeat on a diagonal).

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 15:00, Master = 30:00, Expert = 60:00

Solution: PDF; a solution video from Cracking the Cryptic is here.

Note: Follow this link for other variations on Sudoku.

PDF

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

Theme: XV

Author/Opus: This is the 56th puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Standard Sudoku rules. Also, whenever the numbers in two adjacent cells sum to exactly 10 or 5, an X or V is placed on the edge between cells reflecting the Roman numerals for 10 or 5. All adjacent cells not marked with an X or V cannot add up to 10 or 5.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:00, Master = 7:00, Expert = 14:00

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

Note: Follow this link for other 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.

PDF

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

Theme: Diamond

Author/Opus: This is the 11th puzzle from guest contributor Zoltán Horváth.

Rules: Standard Sudoku rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:45, Master = 2:30, Expert = 5:00

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: X

Author/Opus: This is the 5th puzzle from guest contributor Kishore Kumar Sridharan.

Rules: Standard Sudoku rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:30, Expert = 5:00

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: Ordered Center

Author/Opus: This is the 307th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Sudoku rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:30, Expert = 5:00

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: Borderless

Author/Opus: This is the 9th puzzle from guest contributor Swaroop Guggilam.

Rules: Standard Sudoku rules.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 3:45, Master = 9:00, Expert = 18:00

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

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.