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  • Writer's pictureJacob Cohen

Puzzles from Proofniks & Less-on-Line Sudoku

Hi everyone! Hope you're having a great summer. I've got some grid puzzles to share — and they come from two interesting, different origins!

Puzzles from Proofniks

Toward the end of the school year, I ran a pencil puzzle writing workshop at Proof School! (I went to high school there and absolutely loved it; would strongly recommend for whimsical, mathy Bay Area 6th-12th graders.)

My workshop took the form of a "minicourse," which met on five consecutive Wednesday mornings for 80 minutes. My puzzle-creating students (ranging from 7th to 10th grade) were generally super passionate, creative, and engaged, and I truly believe they produced some top-quality puzzles!

With permission, I've compiled their puzzles into PDF (with commentary) to post here. They include six KenKen (I encouraged them to start with creating that, since I think it's a fairly forgiving puzzle type to create that still has a lot of depth), plus a smattering of other types, including the fascinating Red-Blue Slitherlink. Enjoy!

Printable links:

Or, individual online links:

(Rules: This is like Slitherlink, but instead of one loop, there are two — a red loop, and a blue loop. The two loops can cross, but they can’t share edges. Red clues give the number of red edges; blue clues give the number of blue edges; gray clues give the number of red edges plus the number of blue edges. Draw the two loops!)

Less-on-Line Sudoku

This is my most serendipitous puzzle-writing story ever. It all started with a misclick!

So, I was browsing Manifold and I accidentally followed a random user, Ricki Heicklen. After going to their profile page and unfollowing them, I felt bad that they'd get a fake follower notification, so I figured the least I could do would be to briefly check out their linked website.

The website had a long list of "Unparalleled Misalignments," also known as "quadruple entendres." These are best explained with some examples: "Forest fire // Amazon Kindle," "Economy class // Saving grace," "Fast fashion // Taylor Swift // Quick Fix." Anyway, there was a submission form, and I happened to know that the Crosscord Discord server had a thread where people listed a ton of these (under the name "double doubles"), so I submitted the form, alluding to this.

Ricki Heicklen, as a collector encountering a treasure trove, ended up being quite appreciative. But the serendipitous part for me was this: she was co-running a puzzle hunt for LessOnline 2024, a blogging festival/conference that was held in Berkeley this June, and (based on my online portfolio) invited me to help write it!

I love puzzle hunts, but I know that making them can be a lot of work, so shoutout to Ricki for letting me come to a meeting without having really committed to anything! But after the first meeting, where the plot was explained to me, I became very impressed and excited for the puzzle hunt. It turned out amazing and you should read this narratively infused recap of it.

The hunt had seven metal "tablet puzzles," which had cryptic instructions and served as the keys to seven lockboxes. The puzzle hunt versions are all available in this Drive folder.

I was planning to create a Thermo Sudoku for the hunt, but midway through, I realized it could be rebranded thematically as a Less-on-Line Sudoku — the final piece of serendipity in this story. Then they made my puzzle out of metal!

Here are the links for my Less-on-Line Sudoku specifically:

Online links:

Harder version (this was the original version, and it's visually cleaner, but it's only recommended if you have a lot of sudoku experience)

Printable links:

I hope you enjoy these! As usual, let me know if you encounter any issues.

I'm not sure when I'll post puzzles next; though if you're looking for more, I still have a large archive. (Shoutout to KenGlue, by the way, for solving virtually every Puzzles for Progress puzzle ever, and alerting me to a bunch of random link errors along the way...) In particular, I still strongly recommend the online adaptation of [insert puzzle hunt party here] to anyone who has not done it.

Regardless, bye for now!

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