(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
After the Anti-Windoku by clover! a few days ago, here is a proper Windoku to explore the extra no-repeat rules with full sets of 1-9 going into the gray squares.

PDF

or solve online (using SudokuPad)

Theme: Hedron

Author/Opus: This is the 84th 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). Also, each of the four 3×3 shaded regions must contain the numbers 1 to 9 without repeats.

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 9:00; One party hat (🥳): 18:00. All other solvers earn a 🦕: Geometric Gasosaurus.

Thomas Hits the GAS (highlight to view): 4:01, 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.