The sixth puzzle for the World Sudoku Championship playoffs is another classic Sudoku with a diamond theme by Akash Doulani.

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Theme: Diamond

Author/Opus: This is the 15th puzzle from guest contributor Akash Doulani.

Rules: Standard Sudoku rules.

Estimated Difficulty: 2.5 stars

Solution: PDF for all playoff puzzles.

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 Sudoku including variations can be found in these books in our e-store.

The third World Sudoku Championship playoff puzzle was this Arrow Sudoku from Zoltán Horváth with a visual “podium” theme. All the playoff puzzles represented different themed sudoku rounds and this one represented arithmetic sudoku.

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Theme: WSC Podium

Author/Opus: This is the 19th puzzle from guest contributor Zoltán Horváth.

Rules: Standard Arrow Sudoku rules.

Estimated Difficulty: 2.5-3 stars

Solution: PDF for all playoff puzzles.

Note: Follow this link for more Arrow Sudoku. If you are new to this puzzle type, here are our easiest Arrow Sudoku to get started on. More Arrow Sudoku puzzles can be found in these books in our e-store.

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Theme: Parity Lines

Author/Opus: This is the 7th puzzle from guest contributor R. Kumaresan.

Rules: Standard Sudoku rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:15, Master = 4:30, Expert = 9:00

Solution: PDF and solving video.

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.

Since 2021, we have posted 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 thirteenth Sunday Stumper of 2022 is an unusual Castle Wall puzzle by Stefan Liew where all the clues are on the “Outside”.

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Theme: Outside

Author/Opus: This is the 3rd puzzle from guest contributor Stefan Liew.

Rules: Standard Castle Wall rules.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 11:00, Master = 22:30, Expert = 45:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

This puzzle style, originally published by Nikoli, was part of our first Loop Variety Collection.

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Theme: 2 Many 2×2’s

Author/Opus: This is the 2nd puzzle from guest contributor Martin Ender.

Rules: Draw a single, non-intersecting loop in the grid that enters and exits each bold region exactly once. If a number clue is given in a region, that number indicates the exact number of cells used by the loop in the region. Unused cells cannot be orthogonally adjacent across different regions.

Also, see this example:

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 5:15, Master = 8:15, Expert = 16:30

Solution: PDF and solving video.

Note: Follow this link for other Loop/Path puzzles. More Country Road puzzles can be found in the Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

This puzzle style was created by Martin Ender (first example here), and was one of the “new generation” of puzzles at the 2022 World Puzzle Championship. While it won’t be in our upcoming Loop Variety Collection 2, we are planning to have some more Rail Pool in GMPuzzles projects in the future.

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Theme: Tetris

Author/Opus: This is the 1st puzzle from guest contributor Martin Ender.

Rules: Draw a single, non-intersecting loop that passes through the centers of all cells, including clue cells. Clues represent all of the different lengths of the straight line segments that pass through all cells within the region, either partially or fully contained by that region. Each number within a region must be represented by at least one line segment. Each “?” represents a positive integer; if a clue cell has more than one “?”, all numbers and “?”s in that clue must be different from each other.

Also see this example:

Difficulty: 2.5 stars

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

Solution: PDF and solving video.

Note: Follow this link for other Loop/Path puzzles.

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Theme: Parquet

Author/Opus: This is the 23rd puzzle from guest contributor Bryce Herdt.

Rules: Variation of Nanro rules. Label some cells with numbers to form a single non-intersecting loop; no 2×2 group of cells may be fully labeled, but the loop may touch itself orthogonally or diagonally. The region boundaries divide the loop into segments, and each region must have at least one segment. Numbers denote the length in cells of each segment within a region; all numbers in a region must be the same. When two numbers from different segments are orthogonally adjacent, the numbers must be different. (Consequently, segments in the same region must not share an edge.)

Also see this example:

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 6:15, Master = 9:15, Expert = 18:30

Solution: PDF and solving video.

Note: Follow this link for Nanro puzzles on this website and this link for variations on Nanro puzzles. If you are new to this puzzle type, here are our easiest Nanro Puzzles to get started on. More Nanro puzzles can be found in A Number o’ Nanro by Prasanna Seshadri.

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Theme: Twelve Hexominoes

Author/Opus: This is the 12th puzzle from guest contributor David Altizio.

Rules: Standard Nanro rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:30, Master = 3:45, Expert = 7:30

Solution: PDF and solving video.

Note: Follow this link for Nanro puzzles on this website and this link for variations on Nanro puzzles. If you are new to this puzzle type, here are our easiest Nanro Puzzles to get started on. More Nanro puzzles can be found in A Number o’ Nanro by Prasanna Seshadri.

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Theme: Sudoku Crew

Author/Opus: This is the 4th puzzle from guest contributor Michael Rios.

Rules: Standard Killer Sudoku rules and Thermo-Sudoku rules. Specifically, insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region. Also, 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 thermometer shapes are in the grid; numbers must be strictly increasing from the round bulb to the flat end.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 7:30, Master = 11:15, Expert = 22:30

Solution: PDF and solving video.

Note: Follow this link for more Killer Sudoku and this link for classic Sudoku. More Killer Sudoku puzzles can be found in Killer Sudoku by Serkan Yürekli. 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 Masterpiece Sudoku Mix 2.

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Theme: Antisymmetry

Author/Opus: This is the 20th puzzle from guest contributor Salih Alan.

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 see this example:

Difficulty: 2.5 stars

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

Solution: PDF and solving video.

Note: Follow this link for more Kuromasu puzzles. More Kuromasu can be found in Grandmaster Puzzles Quarterly Vol. 3.