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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.

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Theme: Odd vs. Even

Author/Opus: This is the 103rd puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 2 stars

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

Solution: PDF and solving video.

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

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Theme: Empty Frame

Author/Opus: This is the 398th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Nanro rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:15, Master = 1:45, Expert = 3:30

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: 2×3 Boxes

Author/Opus: This is the 66th puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: (Hybrid of Fillomino and Snake Puzzles.) Divide the grid along the boundary lines so that every cell belongs to a snake. A snake is a one-cell-wide path at least two cells long that does not touch itself, not even diagonally. Circled cells must be at one of the ends of a snake. A snake may contain one circled cell, two circled cells, or no circled cells at all. Numbered cells must be part of a snake with a length of exactly that number of cells. A snake may contain one number, multiple identical numbers, or no numbers at all. Two snakes of the same length cannot touch each other horizontally or vertically. Cells with an X cannot be an end of a snake.

Also see this example:

Difficulty: 1 star

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

Solution: PDF and solving video.

Note: Follow this link for more Snake Pit puzzles. Follow these links for other Fillomino or Snake puzzles.

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 was created by Erhard Notz for the 2019 World Puzzle Championship (innovations round). More Equality puzzles will be in our upcoming Loop Variety Collection 2.

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Theme: Quadrants

Author/Opus: This is the 236th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Draw a single, non-intersecting loop in the grid that passes through some of the white cells. Each bold region must be visited at least twice by the loop. Each visit to the same region must pass through the same number of cells. If a number clue is given in a region, that number indicates the number of cells not used by the loop in that region. The loop cannot pass through gray cells, and gray cells cannot be counted as part of any bold region.

Also see this example:

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 5:45, Master = 9:30, Expert = 19:00

Solution: PDF and solving video.

Note: Follow this link for other Loop/Path puzzles. More Equality puzzles are in the book Loop Variety Collection 2.

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 Naoki Inaba, and will be in our upcoming Loop Variety Collection 2.

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Theme: Pairs

Author/Opus: This is the 102nd puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Draw a single, non-intersecting loop that only consists of horizontal and vertical segments between the dots. The clues in the grid indicate the length of the straight line segment first seen in the direction of the arrow.

Also see this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 4:15, Master = 5:30, Expert = 11:00

Solution: PDF and solving video.

Note: Follow this link for other Loop/Path puzzles. More Line of Sight puzzles are in the book Loop Variety Collection 2.

This puzzle style was created by Robert Vollmert (Geradeweg roughly means “Straight Path” in English). More Geradeweg will be in our upcoming Loop Variety Collection 2.

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Theme: Knight Matrix

Author/Opus: This is the 248th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Draw a single, non-intersecting loop that passes through all cells with circles; the loop may either go straight through or turn at each circle. If the loop goes straight through a circle, the number on that circle indicates the length of the straight segment. If the loop turns at a circle, the number on that circle indicates the length of both loop segments extending from that circle.

Also see this example:

Difficulty: 2.5 stars

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

Solution: PDF and solving video.

Note: Follow this link for other Loop/Path puzzles. More Geradeweg puzzles are in the book Loop Variety Collection 2.

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.