Announcing: The Twelve Days of Sudoku

Twelve Days of Sudoku by Thomas Snyder

Early reviews that chatGPT was probably prompted enough times to finally hallucinate include:

  • “The best thing Snyder’s done to improve understanding of logic puzzle construction since Puzzlecraft
  • “Mostly clueless, certainly too focused on the number forty-five which isn’t the answer to anything, but fun nonetheless”.

Join the discussion on the GMPuzzles Discord.

Note: The puzzle in the image above, a perfect combination of ideas we’ve explored in 2024 (one-star Queens/Star Battle and creative Sudoku), is a Christmas favorite from 2018.

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Added (2:05PM) Several people have asked what kind of sudoku might appear, people who are interested in puzzles and wanted to check in on me as we tend to do at the end of the year (I turn 45 in January and have had a good year, thanks for asking!).

Well, the main series is going to be Classic Sudoku as you know it. Because it is interesting to me for a lot of reasons including testing approaches to competition and puzzle setting / design rules and searching for unexpected things where people have stopped looking.

But I have been thinking of other interesting ideas to share for those who aren’t into classic sudoku puzzles but like other puzzles and things. Ideas that might pop up when I’m also thinking about the silly “is AI coming to take my job” question as I got in a recent interview on LinkedIn. As a creative thinker and problem solver, I can do more with a broken pencil than an AI in puzzle design even if I prefer to work digitally and with software tools and even AI sometimes.

Today, I challenged myself to write the most interesting sudoku I could with just one missing digit. It is a fun prompt to give a puzzle constructor and/or AI because it might not make sense. The image below isn’t my answer. But it is a start.

Twelve Days of Sudoku by Thomas Snyder

I didn’t go smaller, as it turns out I can’t outdo Randall’s Binary Sudoku but that doesn’t have proper regions anyway so I argue this is the absolute smallest for a 1-cell blank puzzle.

And in terms of what is coming, I have written the most interesting 80-given Sudoku-ey thing in history with one missing cell I’d love to see how you’d fill. But it’s not ready to share yet. It is the Ulysses of 1-cell missing Sudoku and before today you didn’t even think about those.

Bonus: Star Battle (also known as Queens) by Thomas Snyder

Earlier this year, Thomas helped provide puzzles for the launch of the LinkedIn game Queens, a very accessible, one-star version of Star Battle puzzles. We have posted some weekly Queens bonuses here through this season, including this puzzle in the form of a hashtag.

Star Battle by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools; in composite Star Battle mode a left click places a star, right click in a cell marks off the cell, and a right click on an edge or corner marks in a dot as a placement note.)

Theme: Hashtag

Author/Opus: This is the 534th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Star Battle rules. One star per row, column, and region.

Difficulty: 2 stars

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

Solution: PDF and solving animation.

Note: Follow this link for other one-star Star Battle puzzles exactly like Queens, and this link for our easiest Star Battles, including many with two stars per region, which are a great way to get started on this version of the puzzle. More Star Battle puzzles can be found in these books in our e-store including our Starter Pack 5: Star Battle book.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Aqre (Symmetry) by Serkan Yürekli

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Aqre (Symmetry) by Serkan Yürekli

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode 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: Into the Unknown

Author/Opus: This is the 506th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Aqre rules. Also, some regions have a circle in their center. In these regions, the shaded cells must have 180° rotational symmetry around the circle of the region. There is no restriction on regions without a circle. A ? can represent any Aqre number clue, including zero.

Aqre Example by Serkan Yürekli

Difficulty: 1 star

Time Standards (highlight to view): Grandmaster = 0:40, Master = 0:50, Expert = 1:40

Solution: PDF and solving animation.

Note: Follow this link for more Aqre puzzles. If you are new to this puzzle type, here are our easiest Aqre to get started on. More Aqre puzzles can be found in these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Slitherlink by Murat Can Tonta

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Slitherlink by Murat Can Tonta

PDF

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: Empty Center

Author/Opus: This is the 305th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Slitherlink rules.

Difficulty: 1.5 stars

Time Standards (highlight to view): Grandmaster = 0:45, Master = 1:15, Expert = 2:30

Solution: PDF and solving animation.

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 these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Fillomino by Grant Fikes

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Fillomino by Grant Fikes

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: Cubicles

Author/Opus: This is the 505th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Fillomino rules.

Difficulty: 1.5 stars

Time Standards (highlight to view): Grandmaster = 0:45, Master = 1:30, Expert = 3:00

Solution: PDF and solving animation.

Note: Follow this link for classic Fillomino and this link for Fillomino variations. 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 these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Battleships by Murat Can Tonta

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Battleships by Murat Can Tonta

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between ship placement and shading modes. In ship placement mode, right click gives sea, left click gives circle/square, left click and drag for rounded ships.)

Theme: 1234

Author/Opus: This is the 304th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Battleships rules. Use the indicated fleet.

Difficulty: 1 star

Time Standards (highlight to view): Grandmaster = 0:25, Master = 0:30, Expert = 1:00

Solution: PDF and solving animation.

Note: Follow this link for classic Battleships and this link for Battleships variations. If you are new to this puzzle type, here are our easiest Battleships to get started on. More Battleships puzzles can be found in these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Tight Fit Sudoku by Serkan Yürekli

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Tight Fit Sudoku by Serkan Yürekli

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku = big entries and Number candidate = small entries in the corners of cells.)

Author/Opus: This is the 505th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Tight Fit Sudoku rules. Remember, the smaller number goes above the larger number in all slashed cells. The range of this puzzle is 1-9.

Difficulty: 1.5 stars

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

Solution: PDF and solving animation.

Note: Follow this link for other Tight Fit Sudoku puzzles on this website. If you are new to this puzzle type, here are our easiest Tight Fit Sudoku to get started on. More Tight Fit Sudoku can be found in these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Math Path by JinHoo Ahn

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

Math Path by JinHoo Ahn

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a number entry mode, a number candidates mode, and a path drawing mode.)

Theme: Tiny Watch

Author/Opus: This is the 131st puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Write a number from 1 to N (N is given for each puzzle) into each cell so that every number appears in the grid once. There must be a path using just adjacent cells to travel between consecutive numbers from 1 to N. Also, the number in the upper-left corner of each bold cage indicates the value of a mathematical operation (addition, subtraction, multiplication, division) applied successively to all numbers in the cage, starting with the largest number for subtraction and division (e.g. 1,2,4 with subtraction is a 1- clue as 4-2-1 = 1). The operation may or may not be given in the cage, but at least one of the four operations must apply.

See also this example:

Math Path example by Thomas Snyder

Difficulty: 1.5 stars

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

Solution: PDF and solving animation.

Note: Follow this link for other Math Path puzzles and this link for other Number Placement variations.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 12 Discussion post on the GMPuzzles Discord.

Bonus: Star Battle (also known as Queens) by Thomas Snyder

Earlier this year, Thomas helped provide puzzles for the launch of the LinkedIn game Queens, a very accessible, one-star version of Star Battle puzzles. We will be posting some weekly Queens bonuses here through this season, including this challenging puzzle formed out of two heart shapes.

Star Battle by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools; in composite Star Battle mode a left click places a star, right click in a cell marks off the cell, and a right click on an edge or corner marks in a dot as a placement note.)

Theme: Two Hearts

Author/Opus: This is the 531st puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Star Battle rules. One star per row, column, and region.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 1:45, Master = 4:00, Expert = 8:00

Solution: PDF and solving animation.

Note: Follow this link for other one-star Star Battle puzzles exactly like Queens, and this link for our easiest Star Battles, including many with two stars per region, which are a great way to get started on this version of the puzzle. More Star Battle puzzles can be found in these books in our e-store including our Starter Pack 5: Star Battle book.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 11 Discussion post on the GMPuzzles Discord.

TomTom (Isometric) by Serkan Yürekli

This is a free “warm-up” puzzle; Season 4 subscribers will see today’s main puzzle in the same style posted at 9:05 AM PT.

TomTom (Isometric) by Serkan Yürekli

PDF

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

Theme: Faces

Author/Opus: This is the 504th puzzle from our managing editor Serkan Yürekli.

Rules: Standard TomTom rules, using the integers 1-8. The “rows” in this puzzle pass through opposite parallel sides of each quadrilateral; in other words, the rows bend across the surface of the apparent cube to travel in a “straight” line.

Difficulty: 1.5 stars

Time Standards (highlight to view): Grandmaster = 1:20, Master = 1:45, Expert = 3:30

Solution: PDF and solving animation.

Note: Follow this link for other TomTom. If you are new to this puzzle type, here are our easiest TomTom to get started on. More TomTom puzzles can be found in these books in our e-store.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Week 11 Discussion post on the GMPuzzles Discord.