Riverbank - Episode 4: Nessie

by Nordy & Henry ‘Pi’ James
published on Friday, 20 May 2022

Rules

• Normal sudoku: Fill every row, column and marked 3×3 box with the digits 1 to 9 once each.
• River & riverbank: Locate a river (think: classic snake) in the grid, consisting of a one-cell wide, non-looping, non-branching string of orthogonally connected cells, which may not touch itself orthogonally (but may diagonally); each border between a river cell and a non-river cell is a riverbank segment (this precludes the grid edge from being counted as riverbank).
• Riverbank sweeper & sentinel: Each circled cell is a riverbank sweeper, which counts riverbank segments within the (up to 3×3) surrounding cells; each squared cell is a riverbank sentinel, which counts riverbank segments in its row and column combined (see example image).
• No negative constraint: Not all circles and squares are necessarily given.

  Puzzle

  

Resources

• Download this puzzle as: scalable image (SVG) | bitmap image (PNG) | printable document (PDF).
  Note: SVG auto-switches colors depending on light/dark mode in system/browser setting; PDF is in printing-friendly black on white.
• Play online on: Penpa+ | CtC App.
• Check your solution and discuss this puzzle with others at LMD puzzle portal.
• Read the walkthrough of this puzzle, scheduled to be published by the weekend of 28-29 May.

Acknowledgment

The (real) debut of riverbank sentinel! @Nordy and I have spent close to a hundred hours combined working on this puzzle - and had so much fun doing it! The break-in, mid- and endgame each went through several rounds of significant change, while the ruleset continues to amaze us with its logical width and depth.

License

This puzzle is published under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.