[This puzzle comes from the 2022 US Sudoku Grand Prix round. This Killer Sudoku was one of my favorite constructions even though I don’t write the style too often. I wanted to get a chain of “last-digit eight” clues into a loop in the grid, and managed to find cage sizes that made good use of 8, 18, 28, and 38 values in this grid. While a few given digits were needed to seed the solving path, that did not diminish the unique “eight” theme visually or logically.]

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Theme: Eight Ouroboros

Author/Opus: This is the 442nd puzzle from Thomas Snyder, aka Dr. Sudoku.

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

Estimated Difficulty: 3.5 stars

Solution: PDF

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.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This variation again uses a double eights theme, both with two large eight shapes and a pair of given eights. I tried to have several different kinds of arrows used across the two eights, with a key question of should an eight be the sum of one or more of the arrows.]

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Theme: Double Eights

Author/Opus: This is the 441st puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Arrow Sudoku rules.

Estimated Difficulty: 3 stars

Solution: PDF

Note: Follow this link for more Arrow Sudoku. If you are new to this puzzle type, here are our easiest Arrow Sudoku to get started on. More Arrow Sudoku puzzles can be found in The Art of Sudoku 2 and Masterpiece Sudoku Mix 3.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This variation again uses a double eights theme, both with two large eight shapes and a pair of given eights in one corner. I like getting complicated consecutive pair patterns that don’t leave a lot of options for singles in some of the regions, and this double eights pattern achieved this goal well to make a fair but difficult competition puzzle.]

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Theme: Double Eights

Author/Opus: This is the 440th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Consecutive Pairs Sudoku rules. (If a gray circle is given between two adjacent cells, then the two numbers in those cells must be consecutive. Note not all gray circles are given; adjacent cells without a circle may contain either consecutive numbers or nonconsecutive numbers.)

Estimated Difficulty: 3 stars

Solution: PDF

Note: Follow this link for Consecutive Pairs Sudoku puzzles on this website. If you are new to this puzzle type, here are our easiest Consecutive Pairs Sudoku to get started on. More Consecutive Pairs Sudoku puzzles can be found in The Art of Sudoku 2 and in Masterpiece Sudoku Mix 6: Consecutive Pairs Sudoku.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This next set of variations uses a shared double eights theme, in this case with both two large eight shapes and at least two given eights. I tried hard to find a unique Thermo-Sudoku pattern that didn’t need the extra non-eight digit in the center cell, but couldn’t get one with a smooth look for the other thermometers. I still liked how the final puzzle got to a moderate difficulty puzzle appropriate for a competition.]

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Theme: Double Eights

Author/Opus: This is the 439th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Thermo-Sudoku rules.

Estimated Difficulty: 3 stars

Solution: PDF

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

[This puzzle comes from the 2022 US Sudoku Grand Prix round. The majority of the sudoku variants had visual “eight” themes as well as interesting logical paths. This Even/Odd Sudoku uses a symmetrical set of even/odd cells in only a few rows and columns in an “eight” shape to highly constrain the grid. I deliberately tried to avoid giving any eights on the outside frame of the grid.]

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Theme: Big Eight

Author/Opus: This is the 438th 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).

Estimated Difficulty: 3 stars

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 and Masterpiece Sudoku Mix 1.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. The majority of the sudoku variants had visual “eight” themes as well as interesting logical paths, and this Tight Fit Sudoku is no exception with one large “eight” given as well as a big eight pattern in the small digits.]

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Theme: Big Eight

Author/Opus: This is the 437th puzzle from Thomas Snyder, aka Dr. Sudoku.

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.

Estimated Difficulty: 2 stars

Solution: PDF

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 our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli, in The Art of Sudoku 2, and in Masterpiece Sudoku Mix 5: Tight Fit 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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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.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This puzzle is the last of three classic Sudoku that did not have a visual theme, however (spoiler for hidden theme and solving path) the digit eight is still a key part of the theme. This is a “just one cell” type Sudoku, one of my trademarks, where the first move is very limited and I’m 99% sure your first digit placement will be an eight in box 8 even if you’ll find it by thinking of other numbers first.]

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Theme: Hidden Theme

Author/Opus: This is the 435th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules.

Estimated Difficulty: 3 stars

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 our e-store, including in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This puzzle is the second of three classic Sudoku that did not have a visual theme, however (spoiler for hidden theme and solving path) the digit eight is still a key part of the theme, one of three isolated digits in their rows/columns that are part of several X-wing patterns in the grid; in this case the eight is not as key initially as the other numbers but it still highlights a way to look at the grid and make progress.]

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Theme: Hidden Theme

Author/Opus: This is the 434th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules.

Estimated Difficulty: 3 stars

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 our e-store, including in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

[This puzzle comes from the 2022 US Sudoku Grand Prix round. This puzzle is the first of three classic Sudoku that did not have a visual theme, however (spoiler for hidden theme and solving path) the digit eight is still a key part of the theme, one of a pair of digits that sets up a lot of pointing pairs in the grid at the start. You can get the center number — an eight — by following just the one number through four symmetric pointing pairs.]

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Theme: Hidden Theme

Author/Opus: This is the 433rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules.

Estimated Difficulty: 2.5 stars

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 our e-store, including in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.