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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.

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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: Uncommon Patterns

Author/Opus: This is the 45th puzzle from our contributing puzzlemaster Tom Collyer.

Rules: Standard Slitherlink rules.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:30, Master = 7:30, Expert = 15:00

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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Theme: Initial Impressions

Author/Opus: This is the 331st puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Sudoku rules. Also, the sum of the numbers in each cage must equal the value given in the upper-left corner of that cage. Numbers cannot repeat inside a cage.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:45, Master = 7:30, Expert = 15:00

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

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.

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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: White Hole

Author/Opus: This is the 306th 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: 4.5 stars

Time Standards (highlight to view): Grandmaster = 13:00, Master = 18:30, Expert = 37:00

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.

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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)

Theme: Pairs

Author/Opus: This is the 184th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Balance Loop rules. Also, numbers outside the grid show the number of separate loop segments visible in that direction. A segment of length N in a given direction is taken as a building of height N. Buildings of height N block the view of all buildings behind them of equal or lesser height.

Also, see this example:

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:30, Master = 7:00, Expert = 14:00

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.

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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: Antisymmetry

Author/Opus: This is the 364th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Cave rules.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 7:45, Master = 12:15, Expert = 24:30

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

Note: Follow this link for other classic Caves and this link for Cave variations. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, 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; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: Singularity

Author/Opus: This is the 6th puzzle from guest contributor William Hu.

Rules: Standard Cave rules.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 3:45, Master = 5:45, Expert = 11:30

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

Note: Follow this link for other classic Caves and this link for Cave variations. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

A written transcript of the audio is here, to reduce the frightful nature of this difficult puzzle after Halloween.
or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a shading mode and a number entry mode to track clues.)

Theme: Ten Out of Ten

Author/Opus: This is the 329th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Cross the Streams rules. Also, (as transcribed from the audio file): “You will hear the clues read to you, first the across clues (starting with the topmost row and moving towards the bottom) and then the down clues (starting with the leftmost column and moving towards the right). In this charming 10×10 puzzle, called “Ten Out of Ten”, grandmaster Grant Fikes demonstrates an affinity for the number 10, using it not just once but twice in the column clues.”

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 9:00, Master = 13:00, Expert = 26:00

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

Note: Follow this link for other Cross the Streams. If you are new to this puzzle type, here are our easiest Cross the Streams to get started on.

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a shading mode and a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

Theme: Foursomes

Author/Opus: This is the 363rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Cross the Streams rules. Also, the shaded region must be able to be split into tetrominoes to form a valid LITS solution (meaning all tetrominoes are connected but no two tetrominoes sharing an edge are the same shape, including rotations and reflections).

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 5:45, Master = 11:00, Expert = 22:00

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

Note: Follow this link for other Cross the Streams. If you are new to this puzzle type, here are our easiest Cross the Streams to get started on.

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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: Keep Away

Author/Opus: This is the 1st puzzle from guest contributor Nate Perkins.

Rules: Standard Fillomino rules. Also, adjacent polyominoes must not have any digits in common (e.g., a 24 polyomino cannot be adjacent to 2, 4, 12, 14, 20, or similar polyominoes).

Difficulty: 4 stars

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

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

Note: Follow this link for other classic Fillomino and this link for more variations on Fillomino puzzles. If you are new to this puzzle type, here are our easiest Fillomino puzzles to get started on. More Fillomino puzzles can be found in The Art of Puzzles, in Fill o’ Fillomino and Fill o’ Fillomino 2 by Grant Fikes, and in our beginner-friendly book Logic Puzzles 101.