Sudoku by Thomas Snyder

Sudoku by Thomas Snyder

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

Theme: Diamonds

Author/Opus: This is the 182nd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules.

Answer String: Enter the 9th row from left to right, followed by a comma, followed by the 9th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 2:20, Master = 3:30, Expert = 7:00

Solution: PDF

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.

Cross the Streams by Murat Can Tonta

Cross The Streams by Murat Can Tonta

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

Theme: Fibonacci Sequence

Author/Opus: This is the 4th puzzle from guest contributor Murat Can Tonta.

Rules: Standard Cross the Streams rules.

Answer String: Enter the length in cells of each of the black segments from top to bottom for the marked columns in the two grids, going in order from A to B to C to D and separating each entry with a comma.

Time Standards (highlight to view): Grandmaster = 5:15, Master = 10:30, Expert = 21:00.

Solution: PDF

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.

Cross the Streams (LITS) by Grant Fikes

Cross The Streams by Grant Fikes

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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: Logical

Author/Opus: This is the 118th puzzle from our contributing puzzlemaster Grant Fikes.

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).

Answer String: Enter the length in cells of each of the black segments from left to right for the marked rows and from top to bottom for the marked columns in the two grids, going in order from A to B to C to D and separating each entry with a comma.

Time Standards (highlight to view): Grandmaster = 5:00, Master = 8:30, Expert = 17:00.

Solution: PDF

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

Cross the Streams (Pentomino) by Grant Fikes

Cross The Streams by Grant Fikes

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

Theme: Logical

Author/Opus: This is the 117th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Cross the Streams rules. Also, the solution has 55 shaded cells which must be divisible into the 11 given pentominoes (rotations and reflections allowed) without overlapping.

Answer String: Enter the length in cells of each of the black segments from left to right for the marked rows and from top to bottom for the marked columns in the two grids, going in order from A to B to C to D and separating each entry with a comma.

Time Standards (highlight to view): Grandmaster = 3:15, Master = 6:00, Expert = 12:00.

Solution: PDF; a solution video is available here.

Note: Follow this link for variations of Cross the Streams and this link for other classic Cross the Streams. If you are new to this puzzle type, here are our easiest Cross the Streams to get started on. Follow this link for other puzzles involving Pentominoes.

Nurikabe (Word) by Thomas Snyder

Word Nurikabe by Thomas Snyder

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or solve online (using our beta test of Penpa-Edit tools; use Tab key to alternate between shading and letter entry)

Theme: Indian States (contributed by GMPuzzles to the Indian Puzzle Championship)

Author/Opus: This is the 180th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Variation of Nurikabe rules. Here, the islands are made up of words given in the list below the grid. The words must appear “snake-like” without forming 2×2 white squares or branching. Each given letter belongs to a separate word from the list. This example from the IPC instructions may be helpful:

Word Nurikabe Example by Prasanna Seshadri

Answer String: Enter the length in cells of each of the black segments (the unnumbered, connected “ocean”) from left to right for the marked rows, starting at the top. Separate each row’s entry from the next with a comma.

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

Solution: PDF; a solution video is available here.

Note: Follow this link for classic Nurikabe puzzles on this website and this link for other variations on Nurikabe puzzles. If you are new to this puzzle type, here are our easiest Nurikabe puzzles to get started on.

Araf by Bram de Laat

Araf by Bram de Laat

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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 shading mode.)

Theme: Clue Symmetry and Logic

Author/Opus: This is the 4th puzzle from guest contributor Bram de Laat.

Rules: Divide the grid into some regions formed of edge-adjacent squares. Each cell is part of one region, and each region should contain exactly two given numbers. Each region must have an area that is strictly between those numbers (This means, for two number clues A and B with A < B, the area C fulfills A < C < B).

Araf Example

Answer String: Enter the number of cells in each connected group (between bold lines) in the marked rows. For the example above, this is “34,121111,4111”.

Time Standards (highlight to view): Grandmaster = 4:40, Master = 6:00, Expert = 12:00

Solution: PDF

Note: Araf is a relatively new puzzle for us on GMPuzzles. Follow this link for other Araf.

Pentominous by Prasanna Seshadri

Pentominous by Prasanna Seshadri

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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 letter entry mode.)

Theme: Clue Symmetry and Logic (Originally on the Indian Puzzle Championship).

Author/Opus: This is the 35th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Divide the grid into 20 pentominoes so that no two pentominoes of the same shape (including rotations/reflections) share an edge. A cell with a letter in it must be part of the pentomino shape normally associated with that letter. An inventory of pentominoes is given below the puzzle but not all shapes must be used.

Answer String: Enter the letter associated with the pentomino occupying each cell in the two marked rows from left to right, separating the rows with a comma. Use CAPITAL LETTERS!

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

Solution: PDF

Note: Follow this link for other puzzles involving Pentominoes.

Slitherlink (Toroidal) by Bram de Laat

Slitherlink by Bram de Laat

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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: Clue Symmetry and Logic

Author/Opus: This is the 3rd puzzle from guest contributor Bram de Laat.

Rules: Standard Slitherlink rules, except that the edges of the grid wrap around. The top row of dots is the same as the bottom row of dots; the left column of dots is the same as the right column of dots. The loop can now run across an outer edge and continue on the other side. This example image may help:

Slitherlink (Toroidal) Example by Thomas Snyder

Answer String: Enter the size of each group of connected squares in the marked rows from left to right; in the example, the bottom row would be “112”.

Time Standards (highlight to view): Grandmaster = 4:20, Master = 6:00, Expert = 12:00

Solution: PDF

Note: Follow this link for other Slitherlink variations and this link for classic Slitherlink. If you are new to this puzzle type, here are our easiest Slitherlink puzzles to get started on.

Slitherlink by Bram de Laat

Slitherlink by Bram de Laat

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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: Clue Symmetry and Logic

Author/Opus: This is the 2nd puzzle from guest contributor Bram de Laat.

Rules: Standard Slitherlink rules.

Answer String: Enter the length in cells of each of the internal loop segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 2:40, Master = 5:40, Expert = 11:20

Solution: PDF

Note: Follow this link for other classic Slitherlink. If you are new to this puzzle type, here are our easiest Slitherlink puzzles to get started on.

Star Battle (Regional) by Prasanna Seshadri

Star Battle by Prasanna Seshadri

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

Theme: UK – site of WPC in 2014 (originally on Indian Puzzle Championship)

Author/Opus: This is the 34th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Variation of Star Battle rules. Place an equal number of stars into each region so that each row and column has two stars. No two stars can touch, even diagonally.

Answer String: For each row from top to bottom, enter the number of the first column from the left where a star appears. Enter these numbers as a single string with no separators.

Time Standards (highlight to view): Grandmaster = 1:15, Master = 3:30, Expert = 7:00

Solution: PDF

Note: Follow this link for other variations on Star Battle and this link for classic Star Battles. If you are new to this puzzle type, here are our easiest Star Battles to get started on.