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or solve online (using our beta test of Penpa-Edit tools; use the tab key to alternate between shading, number entry, and composite loop drawing modes)

Theme: Clockwise

Author/Opus: This is the 21st 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: 4.5 stars

Time Standards (highlight to view): Grandmaster = 5:00, Master = 12:30, Expert = 25:00

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

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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or solve online (using our beta test of Penpa-Edit tools; use the tab key to alternate between shading and number entry modes)

Theme: Tetrominoes

Author/Opus: This is the 359th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Variation of Nanro rules. Label some cells with numbers to form a single connected group of labeled cells. No 2×2 group of cells may be fully labeled. Each label number must be equal to the total count of labeled cells in that bold region, and all bold regions contain at least one labeled cell. The given numbers indicate how many cells are labeled in that region (but not necessarily which cells are labeled). When two label numbers are orthogonally adjacent across a region boundary, the numbers must be different.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 3:00, Master = 4:00, Expert = 8:00

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

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.

This year, we started posting 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 eleventh Sunday Stumper is a challenging (anti-)XV Sudoku by Murat Can Tonta.

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Theme: Pairs

Author/Opus: This is the 214th puzzle from our contributing puzzlemaster Murat Can Tonta.

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: 5 stars

Time Standards (highlight to view): Grandmaster = 17:30, Master = 30:00, Expert = 1:00:00

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.

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

Theme: Five Shurikens

Author/Opus: This is the 36th puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Shade some cells black so that in each region there are exactly four unshaded cells that form an L, I, T, S, or O tetromino. When two unshaded tetrominoes share an edge across regions, they must not be the same shape regardless of rotations or reflections. All shaded cells must be connected into a single group, but no 2×2 group of cells can be entirely shaded black.

Example by Thomas Snyder:

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 12:00, Master = 25:00, Expert = 50:00

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

Note: Follow this link for more variations of LITS and this link for classic LITS. If you are new to this puzzle type, here are our easiest LITS to get started on. More LITS puzzles can be found in LOTS O’ LITS by Grant Fikes and Prasanna Seshadri, in The Art of Puzzles 2, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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

Author/Opus: This is the 212th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Sudoku rules. Also, numbers cannot repeat in any cells separated by a chess knight’s move.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 9:00, Expert = 18:00

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.

(This is a bonus “second” puzzle that is not connected to the usual Monday-Saturday week difficulty. In fact, this is around Sunday Stumper difficulty.)

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Theme: Chi

Author/Opus: This is the 6th puzzle from guest contributor David Altizio.

Rules: Variation of Kakuro Rules. One digit must be duplicated and appear exactly twice in each entry (i.e., group of cells connected horizontally or vertically without any black cells between). All other digits must not repeat within an entry.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 22:30, Master = 37:30, Expert = 1:15:00

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

Note: Follow this link for classic Kakuro and this link for Kakuro variations. More Kakuro puzzles can be found in Kakuro and Variations by Serkan Yürekli and in The Art of Puzzles 2.

(This is a bonus “second” puzzle that is not connected to the usual Monday-Saturday week difficulty.)

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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: No Four in a Row

Author/Opus: This is the 2nd puzzle from guest contributor Matej Uher.

Rules: Standard Slitherlink rules. Also, the letters X and O stand for two different digits from 0 – 3.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 4:00, Expert = 8:00

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.

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Author/Opus: This is the 1st puzzle from guest contributor Matej Uher.

Rules: Place either an ‘X’ or an ‘O’ into each empty cell so that four consecutive ‘X’s or ‘O’s do not appear horizontally, vertically, or diagonally.

Difficulty: 2 stars

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

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

Note: Follow this link for other Number Placement puzzles.

PDF

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

Author/Opus: This is the 10th puzzle from guest contributor Takeya Saikachi.

Rules: Variation of Tapa-Like Loop rules (Form a single non-intersecting loop. Clues inside the grid represent the number of neighboring cells visited by the loop; if there is more than one number in a cell, each number should be represented with a separate loop segment. There is no 2×2 rule of Tapa in this puzzle.). The loop can travel through clue cells. Each clue now describes the entire 3×3 area the clue cell is in the middle of.

See also this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 4:15, Expert = 8:30

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

Note: Follow this link for other Tapa-Like Loop puzzles. More Tapa-Like Loop puzzles can be found in the Tapa-Like Loop Collection by Prasanna Seshadri.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a number entry mode.)

Theme: Noughts and Crosses

Author/Opus: This is the 29th puzzle from guest contributor Joseph Howard.

Rules: 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: 4.5 stars

Time Standards (highlight to view): Grandmaster = 9:30, Master = 14:00, Expert = 28:00

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

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