Silver Plate Sudoku — Play It Online, With the Full Solution

Updated 15 October 2026

Silver Plate is a 21-clue sudoku from the Sudoku Players’ Forum list of the hardest known puzzles, rated SE 11.5 there — a notch below the 11.9 grids at the very top and still far beyond anything a newspaper prints. Play it below, print it, or follow the engine’s solution further down.

Clues

21

Published SE rating

SE 11.5

Suuudokuuu rater

8.5+, past every implemented technique

Play Silver Plate in the appPrint Silver Plate — PDF with the solution

Where Silver Plate comes from

Like Kolk, Silver Plate is one of the named grids in the forum’s long-running “hardest sudokus” thread, the list where solvers collect and rate the hardest grids they find. The figure here is the forum’s published rating, carried by the Suuudokuuu Infinity corpus, not a Suuudokuuu measurement.

Source: Sudoku Players’ Forum, “The hardest sudokus (new thread)”. Every other record grid is on the hardest sudoku puzzles page.

The Silver Plate solution, step by step

Suuudokuuu’s source-available engine solves Silver Plate in 121 steps, reaching for the cheapest technique that still makes progress, exactly as it does when it rates a puzzle. 29 of those steps are forcing chains: the engine assumes a candidate, follows its consequences until something breaks, and removes the assumption. At 2 points even that runs dry — no technique the engine implements moves the grid — and the walkthrough says so, fills the cell with the fewest candidates from the verified solution, and carries on with logic from there. Every other step is a named deduction you can check by hand.

Along the way the walkthrough uses Full House, Naked Single, Hidden Single, Pointing Pair, Box Line Reduction, Naked Pair, Naked Triple, Hidden Pair, X-Wing, Finned Swordfish, Sashimi X-Wing, AIC, Unique Rectangle and Nishio Forcing Chain.