One Cell
Recently, I came across the book "Artisanal Sudoku". I must confess that I've been spending most of my offline time working through its puzzles. They accomplish the rare feat of being both logically approachable and aesthetically pleasing, and on multiple occasions I've found myself impressed by some more abstract realizations that I haven't seen before. I especially look forward to the final chapter, but I'm forcing myself to go in order.
I think the reason I really enjoy variant sudoku and don't often enjoy classic sudoku is because classic sudoku usually isn't set with rigorous deductions in mind. I'd wager that 98% of any uniformly randomly selected classic sudoku is likely solvable with some combination of pointing sets, digits that can only go in one place because the other eight would cause repetition, and places that can only have one digit because the other eight would cause repetition. This is in stark contrast to the flexibility of variant clues, which often require making deeper realizations about what can be true of the set of digits from 1 to 9. One puzzle I solved earlier today from the book puts odd/even clues on a German whisper. I'd never thought of how the clues could play into each other like that before.
Yet, there is one small complaint that I have with variant sudoku in general: once you've satisfied all the variant clues, you're often just left with a trivial classic sudoku. I think I'd appreciate that more if I was better at scanning digits quickly, since I don't have the same distaste for trivial deductions in loop puzzles. I have a hunch that this feeling of wanting to provide a fast way to showcase a cool classic sudoku deduction is what inspired Just One Cell sudoku.
That reminds me. What if instead of using the entire grid to deduce one cell, we use one cell to deduce the entire grid? I set a 4x4 version last year: the page that hosts it is (for reasons I may never discover) the most-viewed post in the entire blog to date. The following puzzle was originally set on the twenty-fourth, although the wording has been adjusted since to make it more streamlined.
- Normal sudoku rules apply. Digits do not repeat in any row, column, or 3-wide-by-2-tall box.
- The digits along the thermo line strictly increase from the end with the bulb to the rounded tip.
- The digits on the arrow line sum to the digit placed in the cell with the circle at the beginning of the arrow line.
- The cells separated by the black dot have a ratio of 2:1. Not all possible black dots are given.
- Digits cannot repeat within the dashed cage and must sum to the given value in the cage.
- The cells separated by the X add to 10. All possible X's are given.