Exclusion (Quadruples) Sudoku by Bill Murphy
(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
For his 75th GAS puzzle on GMPuzzles, Bill brings this creative variation where excluding numbers in surrounding cells drives the main logic.

or solve online (using SudokuPad)
Author/Opus: This is the 75th puzzle from Bill Murphy, 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). Numbers in white circles MUST NOT appear in any of the four surrounding cells.
GAS Time Standards (highlight to view): Two party hats (🎩🥳): 7:00; One party hat (🥳): 13:00. All other solvers earn a 🦕: Outrageous Ornitschian.
Thomas Hits the GAS (highlight to view): 2:06, 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; solving video with explanation to be added later from GAS team.
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.
