Four Corners
(Published on 23. September 2026, 18:15 by dleclair)
Place the digits 1-9 once each in every row and column, except for row 5 and column 5 (where digits may repeat).
Within each corner of the grid is a 4x4 sudoku that may only use 4 different digits. Within each 4x4 sudoku, place the 4 digits once each in every row, column, and box.
There are 4 line types and it must be determined which color of line follows each rule:
Renban: On this line is a set of consecutive, non-repeating digits in any order.
Region Sum: Box borders divide this line into segments. Segments must have equal sums. Lines that don’t cross a box border can have any sum.
German whisper: Along this line adjacent digits differ by at least 5.
Entropy: Along this line any set of 3 adjacent digits must contain one low (123), one middle (456), and one high (789) digit.
Solve in SudokuPad
Solution code: Row 1 (9 digits)
Comments
on 24. September 2026, 08:07 by BigHead
That was a wonderful puzzle, thank you so much for the rule clarification!
on 23. September 2026, 22:46 by jeffrey.l.byrd19
This is a clever puzzle, but I think the rules are a bit confusing around what’s happining in row 5 and column 5. I realized eventually how they worked, but I think maybe an additional note that digits may repeat in C5 and R5. might be helpful.
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Thank you for the feedback, I'll add it in!
on 23. September 2026, 21:06 by BigHead
Could you clarify the rules? R1 contains the digits 1-4 twice - as the 4x4 sudokus are in "each corner". Then r1c5 is one digit that is somewhere from 5 to 9?
Alternatively, r1 contains all of the digits 1-9, because we're meant to place 1-9 in "each row." But then only one of the corners is a 4x4?
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Each of the 4, 4x4 sudokus use 4 digits, but you must determine which 4 digits it uses. So it is still true that every row and column contains the digits 1-9 ultimately. (except row 5 and column 5)
