Sudoku by Thomas Snyder

[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.]

Sudoku by Thomas Snyder


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.

  • bukkanero says:

    hi, I have been following this great blog for a while. I would like to know what those triangles with letters A and B mean, which don’t appear in the on-line solving mode.

    of course, happy 2023 for all the community here.

    • Avatar photo drsudoku says:

      When originally posted, we didn’t share solutions but had an answer checker functionality that involved entering the letters for these rows and columns (you can see these details if you click the original link). Because this is unfamiliar and we don’t want to confuse our solvers, we’ve updated the images to our more recent web style without the arrows.

  • Would it be possible, by any chance, to update some of the older puzzles so that they have star ratings like the newer ones do?

    • Avatar photo drsudoku says:

      Curiously enough, we’ve had several topics of discussions on our internal chat forum about times and star ratings and how these might vary across the years as people get more experience at certain puzzle types, etc. Not a concern for Sudoku or TomTom, but will be something that looks different as we sweep across all the puzzles as our set of testers and also the three time standards we picked varied a bit in the first few months from the rest of the site’s history.

      When originally planning to do some reposts, I didn’t want to make any edits to the original content, but having already removed A/B arrows from the art to simplify design elements we no longer use, I will try to add written star/time ratings to the posts (not put into the images) for rest of the week. They will be more estimates but still pretty close to how we would exactly remeasure them today. We’re not trying to recollect solving info on these puzzles. We’re trying to spend more of our time building some of the next updates to the site.

  • Hashtag says:

    I was just thinking the same thing!

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