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Are you interested in "pure" sudoku? Or are killer, arrow, thermo and so on clues allowed?

There are ones like this - https://app.crackingthecryptic.com/sudoku/6dP4FN27HB (solve https://youtu.be/zfIomUELg6c )

    Normal sudoku rules apply but in the final grid, every clue is wrogn (aka invalid)... 
    Clues are valid if: [Everything is "totally standard" Undar promises...]
    -Digits in a killer cage sum up to the small clue in the top left of the cage;
    -Clues outside the grid are correct X-sums.  ie Clues show the sum of the first X digits in that direction where X is the 1st digit.
    - Clues outside the grid are correct skyscraper clues.  ie The digits in the grid represent the "heights" of skyscrapers. Clues represent the number of skyscrapers seen from that direction. Taller skyscrapers block shorter ones.
    -Digits on a thermometer increase from the bulb end
    -Digits separated by a black dot has a ratio of 1:2
    -Digits separated by a white dot are consecutive
    -Digits separated by X have a sum of 10
    -Digits separated by V have a sum of 5
    -All digits in a circle appear in the 4 cells touching it
    -Maximum cells are larger than all 4 adjacent cells
That one is just crazy... but solvable. Apparently, there's a new one from just a week ago that is similar in construction - https://youtu.be/JTkvR5M0yFo (you'll note the 2h long video)

Another one https://cracking-the-cryptic.web.app/sudoku/pnf623FF7B (solve https://youtu.be/73iEwlTO_p0 )

> Normal sudoku rules apply.

> Group Sums: A number in a small circle indicates the sum of the digits in the cells covered by the corresponding circle. These digits may or may not repeat. Arrow Sudoku: Digits along an arrow must sum to the number in the corresponding circle. In this Sudoku all group sum clues contain a comparison operator. The clue ≥26 for example indicates a sum of at least 26. An arrow between two cells points to the smaller number.

You'll note that I picked a particular channel with the longest videos.

The community around that channel has some particularly difficult puzzles especially if you're willing to go beyond "normal Sudoku rules apply."



Sudoku variants, and even more importantly human-designed puzzles, are where all the fun is.

I grew bored with classic machine-generated sudoku ages ago because it began to feel very mechanical. Adding variant rules like thermometers lets puzzle setters use more bits of logic that are satisfying to reason about.

Puzzle creators are still finding new theorems about how sudoku works, even within the standard rules, and creating puzzles that teach them to solvers. The Phistomephel Ring, an extension of set theory, applies to every single sudoku grid in existence.

As a middling solver, many recently-featured puzzles are too difficult for me, but it’s still fascinating to watch CTC solve them.




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