(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
Three more numbers (13, 14, 15) are here in this Advent Calendar edition of XV Pairs Sudoku.

PDF

or solve online (using SudokuPad)

Author/Opus: This is the 63rd puzzle from Clover, 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). Whenever an X or V, reflecting the Roman numerals for 10 or 5, is placed on the edge between cells, the numbers in the two adjacent cells must sum to exactly 10 or 5. (Pairs of cells without an X or V mark can have any sum value. Also, the cages surrounding some givens are just showing part of the visual theme and have no other meaning.)

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 8:00; One party hat (🥳): 15:00. All other solvers earn a 🦕: Dawdling Domeykosaurus.

Thomas Hits the GAS (highlight to view): 4:09, 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.