(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
The arrows in this grid detect some of the directions where you can find a special sum equal to the original cell’s value. Can you detect all the logic to reach the unique solution?

PDF

or solve online (using SudokuPad)

Author/Opus: This is the 82nd 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). Arrows in the grid indicate that there is a run of cells in the given direction that sums to the number in the cell containing the arrow, starting from the first cell seen by the arrow. Not all arrows are given. (E.g., because R4C2 has an up arrow, either R3C2, R3C2 + R2C2, or R3C2 + R2C2 + R1C2 must sum to the value in R4C2 = 4.)

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 7:00; One party hat (🥳): 13:00. All other solvers earn a 🦕: Deez Darwinsaurus.

Thomas Hits the GAS (highlight to view): 2:54, 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.