Steel Sudoku

Rules

The classic grid on a cold steel plate. Each digit is a tap with a metallic ring behind it, and a completed unit answers with a short bright clang rather than a shatter.

• Each row, column and 3×3 box holds 1–9 exactly once — no extra rules.
• Placements click like a struck plate; the pitch shifts with the column.
• A finished row or box rings out with a longer metallic decay.
• Three difficulties, hints available, progress saved in this browser.

Good to know

Ordinary sudoku rules still apply underneath the variant: every row, column and 3×3 box holds 1–9 exactly once. The extra rule sits on top and is usually what breaks the puzzle open.

More sudoku

All sudoku variants ↗

Or read how to play Sudoku ↗.