Expert Sudoku
Top difficulty — advanced logic or careful trial-and-error.
Expert Sudoku with ~24 starting clues — near the human-solvable minimum. Standard rules: 1–9 in every row, column, and 3×3 box exactly once. At this difficulty you will need XY-wings, swordfish, or uniqueness rectangles to finish without guessing.
Part of: Daily Challenges
How to use
- Rules (unchanged from Easy): fill every blank cell with 1–9 so each row, each column, and each 3×3 box contains every digit exactly once.
- Tap a cell, press 1–9 to place (Backspace/Delete/0 to clear). Red highlight flags a rule break.
- Expect singles and pairs to run out quickly. When they do, move to chains: if A=3 forces B=7 forces C=3 forces a contradiction, then A≠3.
- Every puzzle is uniquely solvable by logic. If you catch yourself guessing, you've missed a technique — rescan from box 1.
- Take breaks: expert solves often need 30+ minutes; state saves per difficulty.
Examples
Before you judge the score
Treat the score as feedback on one short practice round. It may reflect speed, attention, memory, or familiarity with the format, not overall ability.
The best next step is to review one missed pattern or one slow decision, then try a related practice or guide.
Next up
Frequently asked questions
› What is the theoretical minimum clues? Definition
17 clues — proven by exhaustive search in 2012. Most "expert" puzzles hover at 22–24 to stay solvable by humans.
› Can I solve these without guessing? Trust & accuracy
Yes — uniquely-solvable puzzles can always be solved by logic alone, but you may need techniques like XY-Wing, Swordfish, or uniqueness rectangles.
Tips & related reading
See the Daily Challenges hub →Tips & how-tos
- Sudoku Difficulty Explained
- The 15 Best Free Word Games on Kefiw
- Sudoku Difficulty Levels Explained
- A Daily Brain-Health Routine After 40
- Memory Changes After 40: What to Do Next
- Mental Math Practice With Calculators
- How Daily Word Challenges Work
- Daily Streak Tips
- Beginner Sudoku Strategy
- Brain Games for Seniors That Stay Fun Enough to Keep Doing
Relevant links
Related tools
Sudoku
Play Sudoku in your browser. Easy, medium, hard, and expert boards. Auto-save progress.
Hard Sudoku
Play hard Sudoku in your browser. Around 26 clues — requires chains, pairs, and patient elimination.
Medium Sudoku
Play medium Sudoku in your browser. About 30 clues — needs light scanning and candidate elimination.