(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
Will your Fortress Sudoku solving stand, or will it be swept away like a kid’s seaside palace?

PDF

or solve online (using SudokuPad)

Theme: Sandcastles in the Sand

Author/Opus: This is the 142nd puzzle from Philip Newman, part of the Genuinely Approachable Sudoku (GAS) team.

Rules: Standard Sudoku rules (insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region). A number in a gray cell must be larger than any number in an adjacent white cell that shares an edge. (To assist solvers, this is shown like a greater than/less than shape in how the gray cells are drawn.)

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 9:00; One party hat (🥳): 20:00. All other solvers earn a 🦕: Gauche Garumbatitan.

Thomas Hits the GAS (highlight to view): 4:02, with SudokuPad replay file shared as a download for now (requires loading via settings menu with improvements expected before people should use this regularly).

Solution: PDF

Note: Follow this link for other less common variations of Sudoku.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Daily GAS discussion post on the GMPuzzles Discord. Not a member of the Discord? Click this link for basic access.