(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
Can you step to it (by one, up or down) to solve Bill’s Consecutive Killer Sudoku?

PDF

or solve online (using SudokuPad)

Theme: Alone in Cologne

Author/Opus: This is the 90th 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). If a white circle is given between two adjacent cells, then the two numbers in those cells must differ by 1. Pairs of cells without circles can have any relationship. Also, the sum of the numbers in each cage must equal the value given in the upper-left corner of that cage. Numbers cannot repeat inside a cage.

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

Thomas Hits the GAS (highlight to view): 2:10, 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.