What is Anti-Knight Sudoku?

Anti-Knight Sudoku is a challenging variation of the classic sudoku, introducing an extra rule that makes solving the puzzle more complicated. Just like standard sudoku, you must fill in the digits 1 through 9, with each digit appearing exactly once per row, column, and 3×3 block.

What sets this variant apart is the Anti-Knight rule: two cells that are a knight’s move apart (as a knight moves in chess: two squares in one direction and one in another) cannot contain the same digit. This restriction reduces the available positions for certain digits, requiring new strategies to solve the puzzle.

Basic rules of Anti-Knight Sudoku

• As in a regular sudoku, the digits 1 through 9 must uniquely appear in each row, column, and 3×3 block.
• Extra Rule (Anti-Knight): Two cells separated by a knight's move (two squares in one direction and one in the perpendicular direction, as in chess) cannot contain the same digit.

Why does the Anti-Knight rule make sudoku more difficult?

Adding the Anti-Knight rule significantly limits the possible positions for each digit. As a result, players must continuously factor in this additional constraint, making logical deduction and forward-thinking more challenging. Especially at the start of the puzzle, this can create scenarios where it’s less obvious where certain digits should be placed.

Strategies for solving Anti-Knight Sudoku

1. Checking knight moves

Regularly check the knight moves from already filled-in cells to avoid conflicts. Once you place a digit, scan all cells reachable by a knight’s move and mark them as impossible for the same digit, if necessary.

2. Use elimination

Due to the additional Anti-Knight rule, numbers can often be eliminated more quickly, helping you reach logical conclusions faster about where digits should definitely be placed.

3. Think ahead

Sometimes it helps to think a few moves ahead. Consider the implications of placing a digit in a specific cell. If it leads directly to a violation of the Anti-Knight rule elsewhere in the puzzle, you can confidently exclude that digit from that cell.

Who is Anti-Knight Sudoku suitable for?

Anti-Knight Sudoku is perfect for puzzle enthusiasts seeking a new challenge or those already experienced with standard sudoku and other sudoku variants. It demands sharp insight, logical thinking, and a willingness to think a step further than usual.

Whether you're just beginning to explore sudoku variants or you're an experienced puzzler, Anti-Knight Sudoku offers hours of puzzle enjoyment and enhances your logical reasoning skills.

Happy puzzling!