The chess-inspired Sudoku variant — Play free online
Anti-Knight Sudoku follows all standard Sudoku rules, plus one extra constraint: no two identical digits can be a chess knight's move apart (an L-shape: 2 squares in one direction + 1 square perpendicular).
In the diagram above, if the center cell contains a 5, then none of the red cells can also contain a 5.
Anti-Knight Sudoku is a fascinating variant of the classic Sudoku puzzle that adds an extra layer of logical challenge inspired by chess. In addition to the standard Sudoku rules where every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once, this variant introduces the knight constraint: no two cells that are a chess knight's move apart can contain the same digit.
In chess, a knight moves in an L-shape: two squares in one direction and one square perpendicular to that. This means from any given cell on the Sudoku grid, there are up to 8 other cells that are a knight's move away. When you place a number in a cell, you must ensure that same number does not appear in any of those knight-accessible cells, in addition to the usual row, column, and box constraints.
Start with the standard Sudoku techniques you already know: scanning rows, columns, and boxes for missing digits, and using elimination to narrow down possibilities. Then layer on the knight constraint. After placing a digit, immediately check all cells a knight's move away and eliminate that digit as a candidate. Corner and edge cells have fewer knight-move neighbors, making them great starting points. As you progress to harder puzzles, you'll find that the knight constraint actually provides additional information that can help you crack difficult positions that would be ambiguous in standard Sudoku.
Our Anti-Knight Sudoku puzzles come in four difficulty levels. Easy puzzles have more given digits and straightforward logic paths. Medium puzzles require more careful application of the knight constraint. Hard puzzles demand advanced Sudoku techniques combined with deep knight-move analysis. Expert puzzles are designed for seasoned solvers who want the ultimate logical challenge.
Anti-Knight Sudoku offers several unique benefits over standard Sudoku. The additional constraint forces you to think in new patterns, improving your spatial reasoning and logical deduction skills. It bridges two beloved games — Sudoku and chess — creating a hybrid experience that appeals to fans of both. Each puzzle has a unique solution and can be solved purely through logic, never requiring guessing.
We generate fresh Anti-Knight Sudoku puzzles every time you play. Choose your difficulty level and start a new puzzle whenever you like. Track your time, minimize mistakes, and challenge yourself to improve with every game. Whether you're a Sudoku beginner looking for a new twist or an expert seeking a greater challenge, Anti-Knight Sudoku has something for you.