Sudoku, But Hard

Sudoku, But Hard is sudoku for people who find most sudoku apps too easy.

There is no Easy. There is no Medium. Our easiest tier needs locked candidates and pairs, and it only gets worse from there.

FIVE TIERS OF PAIN

• Hard: locked candidates, naked and hidden pairs

• Expert: triples, X-Wings, XY-Wings

• Extreme: Swordfish, coloring, X-Chains, XY-Chains

• Diabolical: alternating inference chains

• Inhuman: the longest chains and almost locked sets

Every puzzle has exactly one solution and is solvable by pure logic: no guessing, ever. Each one is graded by a solver that works the way a human does, so the difficulty label means something.

LEARN THE STRATEGIES

Stuck? Hints don't just fill in a number. They show you the technique that cracks the next step and explain the logic in plain words: X-Wings, Swordfish, XY-Wings, coloring, chains and almost locked sets, with the cells highlighted on the board. Hard sudoku becomes a skill you build, not a wall you hit.

DAILY CHALLENGE

Everyone in the world gets the same puzzle each day. It gets harder through the week, from Expert on Monday to Inhuman on Sunday. Post your time to the leaderboard and see how you rank. Hints cost 30 seconds, so no shortcuts.

STREAKS

Solve the daily puzzle every day to build your streak. Compete on the Longest Streak leaderboard and unlock achievements at 3, 7, 30 and 100 days.

BUILT FOR SOLVING

• Pencil marks

• Hints that explain the technique, step by step

• Undo, erase and auto-notes

• Mistake highlighting

• Digit counters

• Auto-save: pick up exactly where you left off

• Google Play Games leaderboards and achievements

FREE TO PLAY

The first 10 puzzles in every tier are free, and so is the daily challenge, every day, with 3 explained hints a day. Unlock a full tier of 500 puzzles, or all 2,500 at once (with unlimited explained hints), with a one-time purchase. No ads. No subscriptions.