[This is a repost from our archives with new notes at the top: Looking back at past work can show some of the interesting changes with time. For instance, our original GMPuzzles posts like this one from our first week of puzzles used more of a “conversation title/theme” which slowly became just short phrases — or no theme when it was just logical over the years. (Other very obvious updates will include removing the solving arrows, changing solving time standards, and adding in difficulty ratings — we have not tried to make any of those changes this week and have the most stripped down versions of the post here with the goal you might go back to the original.)
There is something refreshing to find after reading that “an exclusively logical theme will be revealed during the solve”. I just went through the puzzle again and found it, but then I have the unfair advantage of better knowing how to read my younger mind. I wonder when I’ll run into a puzzle where past me outsmarts current me.]

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Theme: Besides symmetry, an exclusively logical theme that will be revealed during the solve.

Rules: Standard Sudoku rules.

Estimated Difficulty*: 3.5 stars

Time Standards (highlight to view): Grandmaster = 5:00, Master = 7:30, Expert = 15:00

Solution: PDF and solving video.

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 is a repost from our archives with new notes at the top: This repost from 2013 shows its age as it was a date-themed puzzle, but it might have been the most memorable TomTom in that week because of some less typical logic I found to embed around the repeated numbers. This is where, as a constructor, taking on a rigid theme can force you to explore different kinds of thinking to get to one answer. Yes (highlight to read light spoilers), 13 is always go to be a sum, and 3 is more flexible which will be important, but how do you make some 1’s stand out? The puzzle became the first in our short-lived “Ask Dr. Sudoku” blog post series, a clear inspiration for our future YouTube channel videos. It became harder to keep writing as if I was inside the constructor’s mind when I wasn’t a constructor, but if there is any kind of content this look back is making me want our team to find a way to share more of in 2023+, it is stories like this puzzle, your experience solving it, and then clicking through to the Ask Dr. Sudoku post and seeing how I tell it back — a connection of the solver to the constructor you can’t find easily in any other place.]

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Theme: TomTom for 1/3/13; there are also a few interesting and unusual logical deductions to be found.

Rules: Standard TomTom rules.

Estimated Difficulty*: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:30, Master = 6:15, Expert = 12:30

Solution: PDF

Note: Follow this link for classic TomTom and this link for TomTom variations. If you are new to this puzzle type, here are our easiest TomTom to get started on. More TomTom puzzles can be found in our e-store, including in the TomTom collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

[This is a repost from our archives with new notes at the top about the creation of this puzzle originally on the site ten years ago: Several people have commented to me through the years on the look or feel of a “Snyder Sudoku” — the main example when I think of my own style is something I might share as a new/bonus puzzle on Sunday, from a competition setting and the theme is 100% hard logic right at the start. But other meanings for Snyder Sudoku are about the look of the puzzle standing out too, with esoteric but visually interesting themes far beyond just symmetry — like segregating digits or repeating exact shapes multiple times (like on the cover of The Art of Sudoku four times). When I was constructing the three sudoku for this week initially in 2013, I wanted to make callbacks to different memorable sudoku styles I’d used before in my livejournal days and in this case copied an earlier “missing digit?” idea of mine, with a new composition in the series.]

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Theme: Missing Digit? (opus 2); this avant-garde sudoku poses the question “Is there a 5 in the grid or not?” It is similar to an earlier work by Dr. Sudoku first displayed at the Silicon Valley Puzzle Festival where a different digit, 8, was missing in the same way.

Rules: Standard Sudoku rules.

Estimated Difficulty*: 3 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 6:00, Expert = 12:00

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 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 is a repost from our archives with new notes at the top: We continue our start to 2023 by looking back at our site’s initial puzzle weeks, which balanced Sudoku variations with the ten puzzle styles that would be in The Art of Puzzles. Puzzle #2 was a TomTom, a very special puzzle style to me given how much fun I had experimenting with it in 2009 as I took a mostly computer-generated genre to new places.]

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Theme: “After #1, what’s next?” Many people wondered what would come after post #1 yesterday. Today’s TomTom puzzle is one literal answer, but who knows what the future actually holds?

Rules: Standard TomTom rules; use digits 1-5.

(Estimated*) Difficulty: 1.5 stars

Time Standards* (highlight to view): Grandmaster = 0:40, Master = 1:20, Expert = 2:40

Solution: PDF

Note: Follow this link for classic TomTom and this link for TomTom variations. If you are new to this puzzle type, here are our easiest TomTom to get started on. More TomTom puzzles can be found in our e-store, including in the TomTom collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

*This is trying to recreate our 2020+ type ratings but where our original testing process and number/identity of testers in 2013 was not the same as how we standardized later on in our first year. We’ve made a best effort to bring these historical data to current methodology because people asked for it, but your experience may vary and we aren’t doing “new” testing to reconfirm these times.

[This is a repost from our archives with new notes at the top: As we focus more on website updates and other changes to GMPuzzles — more details to come — we’re starting this year off by looking back at some of our earliest puzzles. Our first new construction when we launched in 2013 was a “Countdown to 2013” Sudoku. Enjoy it again — or for the first time — with digital solving options not available originally.]

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

Theme: Countdown to 2013 – this theme is primarily visual, unlike Dr. Sudoku’s earlier Countdown sudoku theme here.

Rules: Standard Sudoku rules.

(Estimated*) Difficulty: 2.5 stars

Time Standards* (highlight to view): Grandmaster = 2:15, Master = 4:00, Expert = 8:00

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 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 is trying to recreate our 2020+ type ratings but where our original testing process and number/identity of testers in 2013 was not the same as how we standardized later on in our first year. We’ve made a best effort to bring these historical data to current methodology because people asked for it, but your experience may vary and we aren’t doing “new” testing to reconfirm these times.

(view directly for a larger image)

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

Theme: Cross the Streams

Author/Opus: This is the 249th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Kakuro Rules. Also, some cells may remain empty but empty cells cannot share an edge with other empty cells.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 15:30, Master = 20:00, Expert = 40:00

Solution: PDF and solving video.

Note: Follow this link for other Kakuro puzzles. More Kakuro puzzles can be found in Kakuro and Variations by Serkan Yürekli and in The Art of Puzzles 2.

PDF

or solve online (using our beta test of Penpa-Edit tools in Yajilin mode allowing line drawing and cell shading/unmarking; hitting tab can alternate to separate shading and edge drawing modes).

Theme: 2 and 3

Author/Opus: This is the 387th puzzle from our managing editor Serkan Yürekli.

Rules: Locate some automobiles in the grid having size 1×2 or 1×3. Each number in the grid should be part of an automobile, indicating the number of unoccupied cells the automobile can move to by traveling along its longest axis, stopped only by an edge of the grid or another automobile. No more than one number can be in an automobile. (Unlike other variations of this puzzle, there are no extra automobiles without numbers here.)

Also, see this example:

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 5:00, Master = 8:00, Expert = 16:00

Solution: PDF and solving video.

Note: Follow this link for more Parking Lot puzzles.

PDF

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

Theme: Parity Lines

Author/Opus: This is the 7th puzzle from guest contributor R. Kumaresan.

Rules: Standard Sudoku rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:15, Master = 4:30, Expert = 9:00

Solution: PDF and solving video.

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.

PDF

or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)

Theme: Odd vs. Even

Author/Opus: This is the 103rd puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:30, Expert = 5:00

Solution: PDF and solving video.

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; use the tab key to alternate between shading and number entry modes)

Theme: Empty Frame

Author/Opus: This is the 398th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Nanro rules.

Difficulty: 2 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 Nanro puzzles on this website and this link for variations on Nanro puzzles. If you are new to this puzzle type, here are our easiest Nanro Puzzles to get started on. More Nanro puzzles can be found in A Number o’ Nanro by Prasanna Seshadri.