[This is a repost from our archives with new notes at the top (original post here): Greater than/less than constraints can lead to good forcing chains in different number puzzles. However, I’ve never been a fan of using lots of < and > shapes (particularly when rotated 90 degrees) as that notation only works well across pairs of cells and not across chains of connected cells. I created Thermo-Sudoku as a new presentation method to make multi-cell constraints more easily seen and allow for graphically interesting themes. I first developed the style and name while planning for the book Mutant Sudoku with Wei-Hwa Huang, with imagery of a “melted thermometer in the boiling sudoku solution being poured out on paper” as the first mutation caused by Dr. Sudoku’s mistakes in the lab.]

PDF

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

Theme: Grandmaster Puzzles (the G and P shapes in the corners)

Rules: Standard Thermo-Sudoku rules. Range is 1-6.

Estimated Difficulty*: 1 star

Time Standards (highlight to view): Grandmaster = 0:40, Master = 1:00, Expert = 2:00

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 in Masterpiece Sudoku Mix 2.

Our latest “Smashing the Sudoku” video covering the hard Nurikabe and Tight Fit puzzles from last week is now online.

After some extreme weather that caused power outages and then some other challenges, we’re back on track to get through our January tasks including announcing the Best of 2022 puzzles and releasing some bonus Microsoft Puzzle Hunt content. Keep a watch here for those updates and also for the start of discussing our 2023+ plans for the site in the coming weeks.

Puzzle PDF

Author/Opus: This is the 431st puzzle from Thomas Snyder, aka Dr. Sudoku.

Hints: (in rot13):
1. What are these strange puzzle types? Gurl’er glcrf bs ybtvp chmmyrf. Vs lbh frnepu sbe gurve anzrf ba guvf fvgr, gurer ner qrfpevcgvbaf, ubj gb fbyir thvqrf, naq rira ivqrbf.
2. How do I get started? Frira chmmyr glcrf jvgu whfg fvk tevqf? Lbh’yy svefg jnag gb svther bhg ubj rnpu tevq pna havdhryl fbyir nf whfg bar bs gubfr chmmyr glcrf, naq guebhtu fbyivat gur chmmyr vqragvsl gur ? inyhrf juvpu, va nyy pnfrf, ner abg arrqrq gb svaq gur fbyhgvba rkprcg sbe gur snpg gurl ner n pyhr pryy naq va fbzr fglyrf pnaabg or funqrq bire be orybat jvgu nabgure pyhr va na vfynaq/erpgnatyr.
3. How do I figure out which puzzle is which type? Gur tevqf jvgu gur srjrfg pyhrf ner Ahevxnor naq Fuvxnxh naq gur tevq jvgu gur zbfg pyhrf vf n Svyybzvab. Gur erznvavat guerr ner fcyvg npebff Pnir, Xhebznfh, naq Xhebggb. N xrl ybtvpny qrqhpgvba sbe Pnir vf gung lbh pna arire svyy va n purpxreobneq yvxr 2k2 cnggrea bs oynpx naq juvgr fdhnerf (be ryfr lbh jvyy ivbyngr gur pbaarpgvivgl ehyrf). Fb sbphf ba fbzr bs gur 2 pyhrf jvgu qvntbanyyl nqwnprag arvtuobef gb vqragvsl juvpu chmmyr zhfg or gur Pnir.
4. Which puzzle is which type? Sebz hccre yrsg gb ybjre evtug, gur chmmyr glcrf ner: Ahevxnor, Xhebggb; Xhebznfh, Pnir; Svyybzvab; Fuvxnxh.
5. How do I solve the bottom one on the left? Gur obggbz bar ba gur yrsg vf n Svyybzvab chmmyr. Vg znl or n irel uneq chmmyr gb fbyir hagvy lbh erpbtavmr gur tvira pyhrf nyernql nppbhag sbe ng yrnfg 30 (fvk svirf) + 30 (svir fvkrf) + 21 (guerr friraf) pryyf jbegu bs cbylbzvab tebhcf.
6. How do I get a final answer? Gur dhrfgvba znexf va gur qvssrerag tevqf jvyy fgnaq sbe {1,1,6}, {1,2,3,4}, {2,2,3,4}, {2,3,3,5}, {3,3,4,6}, naq {5,6,6,7} juvpu znl uryc vs lbh unir whfg n pbhcyr yrsg hafbyirq. Hfr gurfr inyhrf gb perngr gur 7gu zvffvat chmmyr, gura fbyir vg.

Solution: PDF

Answer String: Enter the final answer (a word or phrase) in ALL CAPITAL LETTERS without spaces to confirm. There may be intermediate answer phrases that are not the final answer; our answer checker is not able to send the message “Keep going” like the Microsoft Hunt solving software does so if you do not see what you expect, treat it like “Keep going” and potentially send an email to us or watch out for hints.

[Note: The remaining two Microsoft Puzzle Hunt puzzles will be released on upcoming future Sundays (starting Jan 29) since these are involved puzzles to solve and harder than our usual weekday content.]

[More comments about the site below; for now, here is the first of four puzzles that I wrote for last year’s Microsoft Puzzle Hunt. Our “Binary Earth” round had paired puzzles that would look similar with a “large thing” and a set of “small things” to look at. This is the easiest puzzle of the set, entitled EXPLORER. Just as at the Microsoft Puzzle Hunt, it is presented solely as a PDF with no specific instructions. I will add hints each day as I also release the other 3 puzzles I wrote for that Hunt this week.]

Puzzle PDF

Author/Opus: This is the 430th puzzle from Thomas Snyder, aka Dr. Sudoku.

Hints (in rot13):
1. What is this puzzle? Gur zrffntr vf qrfpevovat n “Zvarfjrrcre (Cragbzvab)” chmmyr naq gur hahfhny sbeznggvat jvyy or vzcbegnag nsgre fbyivat gung chmmyr (ohg abg orsber).
2. How do I get started? Orpnhfr cragbzvabrf unir znal pbaarpgrq pryyf, fbzr bs gur zbfg xrl pyhrf gb ybbx ng ner gur 1’f va qvssrerag ertvbaf bs gur tevq nf lbh pbafvqre funcrf. Fbzr bs gur cragbzvabrf ng gur gbc ner gur Y, C, naq M juvyr fbzr bs gur cragbzvabrf ng gur obggbz ner gur V, A, naq I.
3. I finished the first part. What now? Rnpu cragbzvab unf n ynory, naq gung zvtug uryc lbh xabj jurer gb ybbx gb svaq bhg jung gb qb ng gur raq.
4. How do I get a final answer? Ernq gur yrggref haqre gur cragbzvab ynoryf gb trg n 12-yrggre vafgehpgvba, gura sbyybj gung vafgehpgvba jvgu gur cragbzvabrf, znxvat ab bgure punatrf, gb erirny gur nafjre.

Solution: PDF

Answer String: Enter the final answer (a word or phrase) in ALL CAPITAL LETTERS without spaces to confirm. There may be intermediate answer phrases that are not the final answer; our answer checker is not able to send the message “Keep going” like the Microsoft Hunt solving software does so if you do not see what you expect, treat it like “Keep going” and potentially send an email to us or watch out for hints.

[Note: I had a very busy weekend, including some mental health care which took me offline completely for 4 days, so have not reformatted the puzzles for this week yet or made the second “Smashing the Sudoku” video either. Amazingly, those busy weekends did not include full completion of the USPC or any participation in the MIT Mystery Hunt so things must be pretty serious for me right now. Reflecting on some of the comments from my post last Thursday, I do not want this site to go completely dark during my sabbatical year, but it may be less predictable when content gets added until we have our other puzzlemasters able to do web tasks more. That said, I also don’t think we need to release more free web puzzles without a new platform that can really grow our audience. Our planning for 2023+ has kicked off in a new GMPuzzles Discord channel that we will open up to authors/top fans soon.]

[This is a repost from our archives with new notes at the top: This Tight Fit Sudoku (original post linked) goes to eleven! While most Tight Fit sudoku use the range of 1-9, these larger grids — in this case one that has already filled all the “big cells” and only has Tight Fit cells left — can stretch your mind and your notation in interesting ways.]

PDF

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

Theme: The patterned digits in this Tight Fit Sudoku set up an interesting logical solve.

Rules: Standard Tight Fit Sudoku rules. Range is 1-11.

Estimated Difficulty*: 3 stars

Time Standards (highlight to view): Grandmaster = 3:45, Master = 7:30, Expert = 15:00

Solution: PDF and solving video.

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 and in The Art of Sudoku 2.

[This is a repost from our archives with new notes at the top: The final Nurikabe (original post) of week two was one of our “best of” puzzles in our launch year 2013, with an interesting visual clock theme and again a different kind of use of wide open white spaces for that unexpected number (if it was going to be anything, it had to be a 13! There might come a time you might need a clock that can point at that).]

PDF

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

Theme: Nurikabe Time; don’t wait for the 13th hour to figure out where all the clock islands go.

Rules: Standard Nurikabe rules.

Estimated Difficulty*: 3 stars

Time Standards (highlight to view): Grandmaster = 2:00, Master = 5:00, Expert = 10:00

Solution: PDF and solving video; advice on solving this puzzle has also been posted in “Ask Dr. Sudoku #2“.

Note: Follow this link for classic Nurikabe and this link for Nurikabe variations. If you are new to this puzzle type, here are our easiest Nurikabe puzzles to get started on. More Nurikabe puzzles can be in The Art of Puzzles, in our beginner-friendly book Logic Puzzles 101, and in the e-book Nurikabe by Ashish Kumar.

(Copying a message below after a day where I’ve felt better than any time in the last 5 years having made a hard life decision. If I haven’t seen you in awhile or written in awhile, this is my commitment this year to share the love with my closest network, to detoxify myself and then to reconnect with my 1000 strongest connections to then see what we can do together on the problems we don’t even know to identify yet. The spark came from thinking about my move to 2014, the story of me ending my (f)unemployment from puzzles and relearning my love of science. It was a letter to Chad. I’ll not share his response unless he agrees, but I want you to know what I’m saying to my close network of people. Writing letters as with a postage stamp may not be a scalable thing to do, but I don’t care right now as it is a great way to share clear thoughts.)

Dear Chad,

There are not enough words (certainly not these 500+) that can say how much I appreciated your love last year, hearing your family connection to mental health while going through a challenging 2022 myself.

You might have seen Verily’s reduction in workforce news. Wednesday was a tough day for me after an exhausting JPM week. I drove to my college alma mater today and cleared my head and feel quite different. It’s added up to the decision in the header, I am taking a sabbatical from full-time work in 2023. I want to slow down parts of my life so that I can speed up my thinking. I want to help change the world, to coach the teams that might be able to.

My first innovative decision is to try life without a cell phone for this year, and connect back with the people I love. I may write a scientific paper after 12 months about the experience on my mental health and on others — I have lots of good measures and I am a data scientist so there could be a story there. Having gone through DBT therapy and being observant has made me recognize even just watching the homeless and mentally ill, or trying to talk to them and seeing how often I can get through — those observations from a person like me could make a difference. I think my main research goal might become tackling mental illness, but January is just about reading non-science books and trying other things.

So to keep me accountable — that this is a sabbatical and not a retirement — I commit this year, every couple months, to write you some thoughtful notes, with no rush for you to respond back (consider it a long letter sent with a postage stamp). I will be visiting different places sometime and I would love to get a set-up like a $1 and 0 equity advisor role just so I can have a badge back if I find myself in Seattle and want a place to sit and do some thinking and don’t need to send any emails to have an open door and a hotel desk. I don’t have an admin, I don’t want an admin. I want an open door like I loved having when I was at google so I could see a foreign city and get a quick snack before heading to an airport if needed. When it is a longer stay, we should certainly arrange an invited talk, a chance for lunch or other connection with you and Harlan.

I have strong connections in 10+ cities, but yours is the only one I want to start with for Seattle, because just talking about immunosequencing with some of its pioneers may revive what I felt in 2014, a time I consider one of the most stimulating in my life as I had access to all your data and to Tableau and could just play. I want my 1-2 day experiments to be things I can share anywhere, and we’ll discuss how this might be possible later. My message today was to just say I made a decision for me and am off the market but also not working anywhere deliberately. I’m going to celebrate my 43rd birthday next Thursday by being with my best friend, their partner, and child, in Boston who I haven’t seen enough since they moved away from SF during my post-hospitalization therapy.

I know we’re not genetically related, but I consider you a dear part of my family — I only use the term for closest connections and mentors/mentees in both directions. I do hope that you are managing these tough times. No rush to respond, but I look forward to a pleasant surprise in my inbox within the next 12 months. And I’ll stand by my commitment to write when I want to share a connection and fun life experience and maybe a new idea where something is connecting in a bigger picture I want to form.

With love,
Thomas

[This is a repost from our archives with new notes at the top: Just as with classic sudoku, themes that look quite unusual (like separations of kinds of digits, far fewer than just 8 digit types, …, are some rich places to explore Tight Fit Sudoku to come up with something that looks unique. Original link here.]

PDF

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

Theme: This Tight Fit Sudoku has separate even/odd right/left sides.

Rules: Standard Tight Fit Sudoku rules. Range is 1-9.

Estimated Difficulty*: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 5:15, Expert = 10:30

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 and in The Art of Sudoku 2.

[This is a repost from our archives with new notes at the top: This Nurikabe (original post) still draws from some aspects of Nikoli puzzles at the start, but by the end starts to apply more global constraints and visualization that is very rarely seen from that publisher. Whether this is that they have a different audience than mine or something else is an interesting discussion. Fifteen years ago I learned from many of the styles/ideas they published; one goal of mine is to see that future generations of solvers draw inspiration from my prior work and my own style of puzzle design.]

PDF

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

Theme: Imbalance – the lower-left is slightly heavier than the upper-right, and is distributed less evenly, affecting the solve.

Rules: Standard Nurikabe rules.

Estimated Difficulty*: 2.5 stars

Time Standards (highlight to view): Grandmaster = 1:30, Master = 3:00, Expert = 6:00

Solution: PDF

Note: Follow this link for classic Nurikabe and this link for Nurikabe variations. If you are new to this puzzle type, here are our easiest Nurikabe puzzles to get started on. More Nurikabe puzzles can be in The Art of Puzzles, in our beginner-friendly book Logic Puzzles 101, and in the e-book Nurikabe by Ashish Kumar.

[This is a repost from our archives with new notes at the top: Our second week of puzzles paired a puzzle type from another company (see yesterday’s post) with Tight Fit Sudoku, a style I originally created for the book Mutant Sudoku. The style actually framed the whole absent-minded scientist concept behind the mutations, as I “adopted” the Dr. Sudoku nickname for myself by telling a story in puzzle form of a chemist making mistakes that led to inventive puzzles. That book by Wei-Hwa Huang and myself (illustrated and edited by Francis Heaney) is one of the best I’ve been a part of, and one goal in 2023 is to start to republish these works that we have rights back for since they’ve been out of print. It looks like this early GMPuzzle is a bit harder than our standard Tuesday difficulties would become, but that is because I wanted the first puzzle to use a few occurrences of the different kinds of thinking that the “tight fit” rule allows. Enjoy!]

PDF

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

Theme: Somewhere Over/Under the Rainbow

Rules: Standard Tight Fit Sudoku rules. Range is 1-8.

Estimated Difficulty*: 2.5 stars

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:45, Expert = 5:30

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 and in The Art of Sudoku 2.