🔁 How to play Palindrome Sudoku

By Miguel Arechaga

Palindrome Sudoku is a very visual variant where gray lines are drawn across the board. The rule is as pretty as its name: the numbers along each line form a palindrome, meaning they read the same from left to right as from right to left. Here are the rules and a few tips.

What is Palindrome Sudoku?

It's a standard 9x9 sudoku with one or more gray lines drawn on it. Along each line, the sequence of numbers must be a palindrome: the first cell equals the last, the second equals the second-to-last, and so on toward the center. The center cell (if the line has odd length) has no pair and can be any value.

Rules and how to play step by step

1. The sudoku rules apply: 1 to 9 without repeats in each row, column and 3x3 box.
2. On each gray line, cells symmetric about the center must hold the same number.
3. You start with some clue cells and fill in the rest with logic. Every puzzle has a unique solution.

Tips to solve Palindrome Sudoku

• Copy between the ends: as soon as you know a number at one end of the line, the other end carries the same one. Propagate toward the center.
• Watch the units: two paired cells can never be in the same row, column or box, since they'd have to repeat a number. The puzzle already guarantees this, but it helps your reasoning.
• The center cell of an odd-length line is free; don't waste time looking for its pair.
• Combine the line equalities with the classic elimination techniques of sudoku.

How it differs from regular sudoku

Compared to classic sudoku, Palindrome introduces equalities between distant cells (the ones on each line), something regular sudoku doesn't control. It's a "line" variant, in the spirit of other line-based puzzles, but with symmetry instead of order. If you enjoy variants with marks, you'll also enjoy Consecutive Sudoku.