Boards with 27 clues · for experienced players · pure logic
A hard sudoku at MundoSudoku starts with only 27 clues. Obvious moves run out quickly: you'll need to work with candidates systematically and apply techniques like naked pairs and box-line eliminations. Always with a unique solution and never any guessing required.
Our guide to advanced sudoku techniques covers naked pairs, candidates and X-Wing with examples, and reviewing common sudoku mistakes will save you many dead ends.
Once hard puzzles fall regularly, expert sudoku awaits — our top level with 23 clues. On Fridays and Saturdays the daily sudoku is hard level: compete against every player. Prefer paper? Print hard sudokus as PDF.
Beyond the basics, you should master naked pairs and triples, hidden candidates and box-line eliminations. With those tools, every hard puzzle at MundoSudoku falls to pure logic.
No. All our boards are generated with a guaranteed unique solution reachable by deduction. If you get stuck, there is usually a hidden candidate you haven't spotted yet — notes are your best ally.
Between 20 and 40 minutes is normal. Expert players solve them in 10-15. The built-in timer keeps your best mark for this level.
You've completed the sudoku.