Logic Masters Deutschland e.V.

Diagramless Number Crossword Sudoku - RSL Edition

(Published on 10. July 2026, 16:05 by RockyRoer)

Even though an earlier version of this type of puzzle didn't garner enough solves to ever recieve a rating - I like this type of puzzle too much to keep this one to myself. I figure, make the kind of puzzles you'd like to find, right? So, here's another one:

The Rules:

  1. [Sudoku]: Normal sudoku rules apply - fill every row and column, and 3x3 region with digits from 1 to 9 once each. Normal sudoku rules apply - fill every row, column, and 3x3 region with the digits from 1 to 9 once each.
  2. [Diagramless Number Crossword]:
    1. Shade some cells in the grid, leaving other cells unshaded. All shaded cells have 180 rotational symmetry. E.g. If R1C3 is shaded, R9C7 is also shaded.
    2. Each unshaded cell is in a block of at least two cells horizontally and at least two cells vertically, like words in a crossword puzzle. Each block is labeled as either an across clue or down clue, with clue numbers always given at the left-most cell of across clues or top-most cell of down clues. These numbers are assigned sequentially, in reading order (from top left to bottom right). Sometimes a number may be used for both an across clue and a down clue (e.g. 14-across and 14-down share the cell containing the 14 clue). A list of all possible clues is given.
    3. Each block must contain within it somewhere its clue number, or in the case of a 2-digit clue number, at least one of those two digits. E.g. 14 across must contain either a 1, or 4, or both. 3-down must contain a 3 somewhere.
  3. [Region Sum Lines]: Some blocks, marked with RSL, must contain a region sum line along the entire length of the line. These blocks must extend into at least 2 regions, and the sum of the digits on the line in each region must be the same. If any horizontal lines intersect with any vertical lines, the lines are considered separate lines and may have different sums.
  4. [Dynamic Fog]: For your convenience, entering correct digits in a few key cells will clear areas of the grid, revealing the underlying clues and shaded cells. This is not intended to reveal anything you hadn't already discovered, but to simply free up pencil marks.

The Puzzle:

Try it using Sven's SudokuPad.

An Example:

I've made a fully solvable 7x7 example if you'd like. Here's a picture of the puzzle, a picture progressing through the solve with the shaded cells, and the final solution.

If you'd like, feel free to read My Solution guide to the 7x7 puzzle. There is some similarity in the solve paths for both puzzles, so if you'd rather not spoiler things, maybe simply try it for yourself on Penpa or using Sven's Sudoku pad

Solution code: 13 Across


Solved by QuiltyAsCharged, ly_ra17, Berkals
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Comments

Last changed on 12. July 2026, 15:08

on 12. July 2026, 13:36 by QuiltyAsCharged
Count me as a fan of this type of puzzle! It's a very clever construction.

I found it challenging to define the structure of the crossword. My first attempt took over an hour and ended in a contradiction. But then I started over, and it went much more smoothly. Now I understood the logic better and it took maybe 25 minutes.

The second phase of filling in the clues wasn't easy either, but it felt more straightforward. Having the clue numbers appear from under the fog was a nice convenience.

Reply: glad you enjoyed it! If you start at the right place (hint: NOT 1 across…) it should be a little more straightforward to construct the clues — hopefully you and future solvers find the intended start. Hit me up with a comment or on discord if you need more of a nudge

Difficulty:3
Rating:N/A
Solved:3 times
Observed:0 times
ID:000TNN

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Solution code:

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