The last two closing puzzles of the World Sudoku Championship playoffs were very tricky, starting with this hybrid of Clone and Shape Sudoku by Joseph Howard.

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Theme: 8 Rings

Author/Opus: This is the 33rd puzzle from guest contributor Joseph Howard.

Rules: Combination of Shape and Clone Sudoku rules. Insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region. Also, there are some numbered shapes that must be put into the grid. Shapes can be rotated, but cannot be reflected. Each shape outside the grid must appear exactly once inside the grid. Also, all remaining shaded regions of the same shape (“clones”) must be able to be paired together to include the same numbers in the same positions.

Estimated Difficulty: 3.5 stars

Solution: PDF for all playoff puzzles.

Note: Follow this link for more variations of Sudoku.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. Shape Sudoku is a variation I created many years ago where careful assignment of the givens to each of the shapes can lead to fun and narrow solving paths, so I really enjoy setting these kinds of puzzles. I had one big idea for the “eight” theme which you’ll certainly see while working through to the solution.]

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Big Eight

Author/Opus: This is the 436th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Shape Sudoku rules.

Estimated Difficulty: 4 stars

Solution: PDF

Note: Follow this link for other Shape Sudoku. More Shape Sudoku are in Masterpiece Sudoku Mix 8.

Since 2021, we have posted 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 eighth Sunday Stumper of 2022 is a Shape Sudoku by Salih Alan with a “Multiplication” theme in each of the shapes; while it might be a touch easier at 4.5 stars than some of our other stumpers, we expect you’ll still enjoy figuring out the intended solving path.

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Multiplication

Author/Opus: This is the 16th puzzle from guest contributor Salih Alan.

Rules: Standard Shape Sudoku rules.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 9:00, Master = 15:00, Expert = 30:00

Solution: PDF and solving video.

Note: Follow this link for other Shape Sudoku. More Shape Sudoku are in Masterpiece Sudoku Mix 8.

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Offset Frame

Author/Opus: This is the 418th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Shape Sudoku rules.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 8:30, Master = 13:00, Expert = 26:00

Solution: PDF and solving video.

Note: Follow this link for other Shape Sudoku. More Shape Sudoku are in Masterpiece Sudoku Mix 8.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Goalkeeper

Author/Opus: This is the 374th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Shape Sudoku rules.

Difficulty: 1.5 stars

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

Solution: PDF and solving video.

Note: Follow this link for other Shape Sudoku. More Shape Sudoku are in Masterpiece Sudoku Mix 8.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Four Squares (Originally on 2017 Brand’s Sudoku Open)

Author/Opus: This is the 167th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Shape Sudoku rules.

Answer String: Enter the 5th row from left to right, followed by a comma, followed by the 7th row from left to right.

Time Standards (highlight to view): Grandmaster = 4:15, Master = 11:45, Expert = 23:30

Solution: PDF

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: Diamonds (for Chris Green)

Author/Opus: This is the 150th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Classic Sudoku Rules. Also, some arrow shapes are in the grid; the sum of the digits along the path of each arrow must equal the digit in the circled cell. Some thermometer shapes are in the grid; digits must be strictly increasing from the round bulb to each flat end. Finally, some diamond shapes are in the grid; the labeled diamonds below the grid must be placed in some order onto the shapes in the grid. The labeled diamonds can be rotated but cannot be reflected.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 5:15, Master = 10:45, Expert = 21:30

Solution: PDF

Note: 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. More Arrow and Thermo-Sudoku puzzles can be found in The Art of Sudoku 2.

(View image directly for larger form.)

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and two drawing modes, Special and Surface, to mark the shape inventory.)

Theme: Snakes on a Sudoku

Author/Opus: This is the 16th puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Sudoku rules. Also, there are some shapes that must be put into the grid. The shapes can be rotated, but cannot be reflected; they can touch but cannot overlap. (Not all cells of the shapes contain numbers, but all numbers on the shapes must be entered into the corresponding cells after placement.)

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 8th row from left to right.

Time Standards (highlight to view): Grandmaster = 10:00, Master = 30:00, Expert = 60:00

Solution: PDF

Note: 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.

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and two modes, Shape and Surface, to manage the domino inventory.)

Theme: Double Domino
(Hidden shapes include a complete double-eight domino set. Double dominoes have been “doubled over” to fit within one square. Hidden names include J.S. Bach, Gabriel Faure, John Cage, and various chordal progressions and crossword game vocabulary.)

Author/Opus: This is the 9th puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Sudoku rules, using the letters A-H and a blank. Also, as in Shape Sudoku, there are some lettered shapes given beneath the grid that must be put in their proper places inside the grid; and, as in Battleship Sudoku, their proper places are indicated only partially. (Partial shape clues in the grid are not lettered but do not necessarily indicate the location of blanks.) The shapes can be rotated, but cannot be reflected; they can touch but cannot overlap.

Answer String: Enter the 3rd row from left to right, followed by a comma, followed by the 3rd column from top to bottom. (Use the capital letters A-H; use X for a blank.)

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

Solution: PDF

Note: 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.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

Theme: Zero X

Author/Opus: This is the 56th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Shape Sudoku rules.

Answer String: Enter the 2nd column from top to bottom, followed by a comma, followed by the 5th column from top to bottom.

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

Solution: PDF

Note: Follow this link for other less common variations of Sudoku. Many specific variations of Sudoku have their own categories in the sidebar to the left. Follow this link for classic Sudoku.