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

Theme: Two-Sided Problem

Author/Opus: This is the 187th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Even/Odd Sudoku rules (i.e., cells with a square contain an even digit; cells with a circle contain an odd digit).

Answer String: Enter the 4th row from left to right, followed by a comma, followed by the 2nd column from top to bottom.

Time Standards (highlight to view): Grandmaster = 3:45, Master = 8:00, Expert = 16:00

Solution: PDF

Note: Follow this link for more Even/Odd Sudoku puzzles. If you are new to this puzzle type, here are our easiest Even/Odd Sudoku to get started on. More Even/Odd Sudoku puzzles can be found in The Art of Sudoku 2.

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

Theme: 1, 2, Star, ?

Author/Opus: This is the 6th 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 = 5:00, Master = 10:00, Expert = 20:00.

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.

PDF

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

Theme: Sudoku GP Round 7, plus two hidden themes related to 7
(Note: this puzzle was originally created for the Sudoku Grand Prix but after testing was judged too hard and too puzzle-based for the competition. It is an excellent puzzle, and we are proud to showcase it here.)

Author/Opus: This is the 40th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Sudoku rules. Also, standard Skyscrapers rules. Additionally, the cells in gray are “underground” and cannot be seen by any of the outside skyscraper clues (think of them as starting with a negative sign if necessary). As an example, the 3 on the left of row 2 refers only to seeing three buildings in columns 2 through 9, even if there is a 9 in column 1 as that 9 cannot be seen.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 5th row from left to right.

Time Standards (highlight to view): Grandmaster = 7:00, Master = 10:00, Expert = 20:00

Solution: PDF

Note: Follow this link for our first Basement Skyscraper Sudoku. Follow this link for other less common 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.

Note: When we said everything was a lie in last week’s schedule, that included there being just 6 puzzles. Enjoy this bonus ‘Sunday’ challenge from Prasanna.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode, a number entry mode for placing Tapa clues, and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)

Theme: Clue Symmetry and Logic

Author/Opus: This is the 38th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Variation of Tapa Rules. Every given clue is lying in two ways: first, the number of given clues in that cell is false; second, the value of any given clues is not true for any part of the Tapa around that cell. For example, a 3 clue could actually indicate 24, but it could not indicate 2 (same number of clues) or 23 (the digit 3 appears). 0 is not a valid clue for this Tapa.

Answer String: Enter the length in cells of each of the shaded segments 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 = 8:00, Master = 16:00, Expert = 32:00

Solution: PDF

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

PDF

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

Theme: Logical

Author/Opus: This is the 123rd puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Variation of Cross the Streams rules. Some groups of outside clues are lying and refer to the white cells in that row/column, not the black cells. It is up to you to determine which clue groups are lies. (It is possible for a clue group to be true for both the white and black cells in that row/column.)

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 = 5:30, Master = 9:00, Expert = 18:00

Solution: PDF

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

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 letter entry mode.)

Theme: Words

Author/Opus: This is the 55th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Divide the grid into 20 regions each containing 5 cells. Regions with the same shape (including rotations/reflections) cannot share an edge. A region may contain at most one letter clue. Each letter is false; the correct letter which indicates the shape of that pentomino is either one higher or one lower in alphabetical order (for instance, a P clue could be an N or a T pentomino).

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 = 5:45, Master = 7:30, Expert = 15:00

Solution: PDF

Note: Follow this link for other puzzles involving Pentominoes.

(View image directly for larger form.)

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

Theme: Big Twister

Author/Opus: This is the 4th puzzle from guest contributor Tapio Saarinen. You can find more of his puzzles on Perplexible.

Rules: Standard Nurikabe rules.

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. Separate each row’s entry from the next with a comma.

Time Standards (highlight to view): Grandmaster = 12:00, Master = 21:00, Expert = 42:00

Solution: PDF; a solution video is available here.

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

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

Theme: One, Two

Author/Opus: This is the 3rd puzzle from guest contributor Tapio Saarinen, including one earlier Outside Nurikabe. You can find more of his puzzles on Perplexible.

Rules: In this variation of Nurikabe, the island clues are now given outside the grid. These numbers must be placed in the first white island cell encountered in the corresponding direction. Each number represents a distinct island, with a total of 23 islands in this puzzle.

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. Separate each row’s entry from the next with a comma.

Time Standards (highlight to view): Grandmaster = 4:15, Master = 10:00, Expert = 20:00

Solution: PDF

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.

(view image directly for larger form)

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 shading mode.)

Theme: Infinity!

Author/Opus: This is the 51st puzzle from our contributing puzzlemaster Serkan Yürekli.

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).

Answer String: Enter the number of cells in each connected group (between bold lines) in the marked rows. If a group is a multi-digit number, enter all digits of that number. For the example above, the entry is “34,121111,4111”.

Time Standards (highlight to view): Grandmaster = 8:00, Master = 15:00, Expert = 30:00

Solution: PDF

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

(view image directly for larger form)

PDF

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Theme: Stars and Stripes

Author/Opus: This is the 183rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Star Battle rules. Three stars per row, column, and region.

Answer String: Enter the column letter of the MIDDLE STAR in each row, going from top to bottom. Use capital letters only.

Time Standards (highlight to view): Grandmaster = 5:00, Master = 6:15, Expert = 12:30

Solution: PDF; a solution video is available here.

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