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: Evens

Author/Opus: This is the 192nd puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Statue Park rules. Also, an even number of cells in each row and in each column must be occupied by pentomino shapes.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 9:30, Master = 17:00, Expert = 34:00

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

Note: Follow this link for other classic Statue Park and this link for Statue Park variations. If you are new to this puzzle type, here are our easiest Statue Parks to get started on. More Statue Park puzzles can be found in the ebook Statue Park by Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)

Theme: Avoid the Edge

Author/Opus: This is the 339th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Tapa rules. Also, an even number of cells must be shaded in each row and in each column.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 2:30, Master = 8:30, Expert = 17:00

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

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

PDF

or solve online (using our beta test of Penpa-Edit tools in edgex mode where left click+drag draws lines and right click marks X’s)

Theme: Clock

Author/Opus: This is the 74th puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Slitherlink rules. Also, an even number of cells in each row and in each column must be inside the loop.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 3:45, Master = 5:00, Expert = 10:00

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

Note: Follow this link for classic Slitherlink and this link for Slitherlink variations. If you are new to this puzzle type, here are our easiest Slitherlink puzzles to get started on. More Slitherlink puzzles can be found in The Art of Puzzles, Slitherlink and Variations, and our beginner-friendly book Logic Puzzles 101.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: Missing 5

Author/Opus: This is the 202nd puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Shade some empty cells black so that each number indicates the total count of white cells connected vertically and horizontally to that number including the numbered cell itself. Black cells cannot share an edge, and all white cells must belong to a single connected group. Also, an even number of cells must be shaded in each row and in each column.

Also see this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 3:00, Master = 4:45, Expert = 9:30

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

Note: Follow this link for more Kuromasu puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between ship placement and shading modes. In ship placement mode, right click gives sea, left click gives circle/square, left click and drag for rounded ships.)

Theme: Invisible Outer Clues

Author/Opus: This is the 319th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Battleships rules. Also, an even number of cells in each row and in each column must be occupied by ship segments.

Difficulty: 2 stars

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

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

Note: Follow this link for classic Battleships and this link for Battleships variations. If you are new to this puzzle type, here are our easiest Battleships to get started on. More Battleships puzzles can be found in Battleships and Variations, in The Art of Puzzles, 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: Target One

Author/Opus: This is the 61st puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Standard Yajilin rules. Also, an even number of cells must be shaded in each row and in each column.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:15, Master = 2:00, Expert = 4:00

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

Note: Follow this link for classic Yajilin and this link for Yajilin variations. If you are new to this puzzle type, here are our easiest Yajilin to get started on. More Yajilin puzzles can be found in The Art of Puzzles 2, in Yajilin by Murat Can Tonta and Prasanna Seshadri, and in our beginner-friendly book Logic Puzzles 101.

PDF

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

Theme: Tetromino Z

Author/Opus: This is the 318th puzzle from our managing editor Serkan Yürekli.

Rules: Standard TomTom rules, using the integers 1-6. Also, standard Skyscrapers rules.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 6:00, Master = 10:15, Expert = 20:30

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

Note: Follow this link for classic TomTom and this link for TomTom variations. Follow this link for classic Skyscrapers puzzles and this link for variations on Skyscrapers puzzles. More TomTom puzzles can be found in the TomTom collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Prasanna is celebrating two milestones this week and we will have two special large puzzles. The first one here recognizes Prasanna’s 200th submission on GMPuzzles, and combines three of the styles where Prasanna has written books for our e-store.

(view directly for a larger image)

PDF

or solve online (using our beta test of Penpa-Edit tools; while solution checking is not enabled, if you are comfortable with the different tool selection options you should be able to fully solve the puzzle in this mode too.)

Theme: Linking 200 cells

Author/Opus: This is the 200th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules:

Grids 1-2: Follow regular LITS rules. Between the two LITS grids, the corresponding white cells can never both be shaded, while the corresponding gray cells must be identical in the three 200-shaped regions.

Use the LITS solutions and your ingenuity to discover the needed constraints for Grids 3-4. For Grid 3, you will find that some gray circles must change color to white or black.

Grid 3: Follow regular Balance Loop rules. Additionally, the loop must cross itself if it passes through a gray circle. The loop must go straight throught the gray circle both times; in one direction the path behaves as if the circle is white with equal loop lengths, and in the other direction the path behaves as if the circle is black with unequal loop lengths. It is not required that the loop pass through all of the gray circles (but it must pass through all white and black circles). (See also the image below.)

Grid 4: Follow regular Yajilin rules.

When taken together, the grids yield a short final answer! Send this (less than five character) string to hiddencontest at gmpuzzles dot com by March 14th, 2021 to be eligible to win an e-book by Prasanna Seshadri. The contest is now closed and results summarized here.

Difficulty: 5 stars?

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode, shape (star) placing mode, and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: Only 4 You

Author/Opus: This is the 317th puzzle from our managing editor Serkan Yürekli.

Rules: (Standard Balance Loop rules.) Also, each row and column must contain exactly two stars. Stars cannot be placed in adjacent cells that share an edge or corner, and all stars must be on empty cells not used by the loop.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 7:30, Master = 13:15, Expert = 26:30

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

Note: Follow this link for other Balance Loop puzzles. If you are new to this puzzle type, here are our easiest Balance Loop Puzzles to get started on. More Balance Loops can be found in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli and in Balance Loop by Prasanna Seshadri and Murat Can Tonta.