(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
This quirky combo is new to GAS, though its components aren’t: clues outside the grid are both X-Sums and Sandwich clues!

PDF

or solve online (using SudokuPad)

Author/Opus: This is the 80th 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). The clues outside the grid indicate the sum of the first X numbers placed in the corresponding direction, where X is equal to the first number placed in that direction (e.g., if R9C3 is 4, then the four numbers in R9C3 (i.e., 4), R8C3, R7C3, and R6C3 all add up to 10). Clues outside the grid also give the sum of numbers in the cells between the 1 and the 9 in that row or column.

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 6:30; One party hat (🥳): 13:00. All other solvers earn a 🦕: Mixed Megapleurocoelus.

Thomas Hits the GAS (highlight to view): 4:00, 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.