(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
Colonizing Mars or the Moon sounds more like a matter of when than if these days, so perhaps we earthlings are the true space invaders. Get ahead of the trend by populating the grid of this Palindrome Sudoku.

PDF

or solve online (using SudokuPad)

Theme: Space Invader

Author/Opus: This is the 170th 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). The numbers along each gray line form a palindrome (i.e., read the same forwards and backwards).

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

Thomas Hits the GAS (highlight to view): 2:44, 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

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.