Box Brain Sudoku

New on the App Store

Twelve kinds of sudoku.
Hints that teach.

Classic when you want the familiar. Killer, Thermo or Kropki when you want something new. And a hint that shows you why, not just what.

Download on theApp Store Try a puzzle here first ↓
  • iPhone
  • iPad
  • iPhone Duo

Free to play · No account · No subscription

Play it right here

Nine cells left. Can you finish it?

Tap a cell, then a digit. Stuck? Tap Hint: like in the app, it names the technique and shows you why the move works.

Try a skin Studio

Twenty skins in the app, and you can try any of them for a whole game before you buy.

Today's puzzle A new puzzle every day, a different mode each time, plus all twelve modes to play in your browser. Play today's puzzle →
Classic · Easy00:00

Pick an empty cell to start.

12 ways to play

One calm app, twelve kinds of sudoku

Every puzzle has exactly one solution and can be solved by logic alone. Difficulty is rated by the techniques a puzzle needs, so Hard means hard.

  • Classic

    Every row, column and 3×3 box holds 1 to 9 once.

  • Killer

    Dashed cages show the sum of their digits, with no repeats inside.

  • Jigsaw

    Odd-shaped regions take the place of the 3×3 boxes.

  • Thermo

    Digits climb from the bulb to the tip of each thermometer.

  • Arrow

    The digits along an arrow add up to the number in its circle.

  • Sandwich

    Clues give the sum of the digits between the 1 and the 9.

  • Kropki

    White dots join consecutive digits, black dots join a digit and its double.

  • Greater Than

    Signs between cells tell you which digit is bigger.

  • Diagonal

    Both long diagonals also hold 1 to 9 once each.

  • Hyper

    Four extra shaded boxes also hold 1 to 9.

  • Anti-Knight

    The same digit can't sit a chess knight's move away.

  • Even-Odd

    Shaded squares hold even digits, circled cells hold odd ones.

How to play each mode, with tips →

Inside the app

Calm on the surface. Deep underneath.

  1. 01

    A hint that teaches, not tells

    Ask for help and the app first points you to the right row, column or box. Ask again and it names the technique and shows the move, so next time you won't need it.

    A Killer puzzle with a Hidden Single hint explained under the board
  2. 02

    Your day at a glance

    Today's two dailies, the weekly Expert challenge and this month's goals, all on one calm screen. Pick up where you left off in a tap.

    The Today screen with the dailies, the weekly challenge and monthly goals
  3. 03

    A streak worth keeping

    A calendar of every daily you've solved. Earn a streak saver every seven days, and a missed day is covered.

    The daily calendar with solved days and the current streak
  4. 04

    Twenty skins, day and night

    From paper-calm Studio to near-black Night Lab and bright Neon. Try any skin for a game before you decide.

    Night LabNeonSakuraForestStudio
    A puzzle in the dark Night Lab skin
Everything in the box

Small details, all the way down

Built by people who play every day. Here's what's inside, beyond the twelve modes.

Notes, your way

Corner and centre notes, and digit-first entry: hold a number, then tap cells.

Three ways to play

Relaxed, with mistake checking, or a three-mistake challenge. Hide the clock if you like; your times are still saved.

Streak savers

Earn one every seven days. Miss a day and it's covered.

Widget and reminder

Today's dailies on your home screen, and a gentle once-a-day nudge if you want one.

See yourself improve

Best and average times for every mode and difficulty, personal bests and flawless solves. Your skill page shows which techniques slow you down.

Progress that follows you

Synced through iCloud, with a backup file for a new phone. Achievements, leaderboards and your Game Center friends' times too.

Pro

For the deep end

Everything free stays free. Pro adds the tools serious solvers reach for, for $9.99 once. No subscription.

See what's free and what's Pro →
Off the screen

Print it, emboss it, share it

Sudoku doesn't have to stay on your phone. Make a book for a long flight, a sheet for a classroom, or a puzzle you can read with your fingers.

Puzzle books as a PDF

New puzzles in any mode and difficulty, one, two or four to a page. Ink-friendly on any paper size, with the answers on the last pages. Good for travel, classrooms and screen-free time.

Pro

Braille sheets

A .brf file ready to emboss or read on a braille display, or a swell-paper PDF of raised dots at standard braille spacing. For Classic, Diagonal, Hyper and Anti-Knight.

Free for everyone

Share and challenge

Share a finished solve as an image, or send the starting board as a challenge link: your friend gets the same puzzle and your time to beat.

Free
Free sheets, made right herePrint puzzles in any of the 12 modes, or download braille for embossers and swell paper. New puzzles every time, answers included, no account. Make free sheets →
Two dailies, every day

The same puzzles for everyone

A Classic and a featured mode every day. Keep your streak, with a streak saver for the day life gets in the way.

  • A weekly Expert challenge and monthly goals that earn an exclusive skin.
  • Achievements and Game Center leaderboards.
  • Challenge a friend with a link to the same puzzle and see who is faster.
Made for every screen

One board. Every shape of iPhone and iPad.

On iPad and the open iPhone Duo, the board and keys sit side by side in landscape. On Duo your game carries on as you fold, unfold or turn it.

  • iPhoneEvery size, one hand or two
  • iPadRoom for the board, keys and notes
  • iPhone DuoFolded or open, the board fits
Made for everyone

Play it without seeing the board

Full VoiceOver support: every cell reads its clues, and you can hear a row, column or box and enter, note or erase digits by ear. Read aloud speaks each move without a screen reader.

  • One-tap setups for low vision and colour blindness.
  • Shapes that never rely on colour alone, and a free High Contrast skin.
  • Support for Bold Text, larger text and Reduce Motion.
  • Braille sheets for embossers and swell paper, free for everyone. See printing

Every accessibility feature →

Fair pricing

Free to play. Pay once if you love it.

No account, no energy, no subscription. The free version shows a small banner and never a full-screen ad you didn't ask for.

Free

$0
Plenty to play every day, no time limit
  • Unlimited Classic
  • Both dailies, every day, and the last 7 days
  • The weekly challenge, monthly goals and achievements
  • One free puzzle of every other mode
  • 3 explained hints per puzzle, and more for a short video
  • Lessons for every technique, and a first practice set
  • Studio, Night Lab and High Contrast skins, and a free trial of every other skin
  • Challenge links, Game Center, iCloud sync and the widget
  • Every accessibility feature, Read aloud and braille sheets

Pro Best value

$9.99
One-time, not a subscription
  • Unlimited play in all twelve modes
  • No ads, ever
  • Unlimited explained hints
  • The full daily archive
  • All twenty skins
  • Printable puzzle books with answer keys
  • Explained mistakes, fill all notes, colour marks, stats export

Skins pack

$2.99
One-time, for just the looks
  • Every skin unlocked, from Zen to Cyberpunk
  • Try any skin for a game first

Accessibility is never behind a paywall. Purchases restore on every device signed in to the same Apple Account. Prices are in US dollars and vary by country.

Private by design

No account and no servers holding your data. Progress stays on your device and in your own iCloud, with a backup file for a new phone.

Print and share

Share your solve as an image. With Pro, print puzzle books as a PDF in any mode and difficulty, with an answer key.

Eight languages

English, Spanish, Portuguese, German, French, Italian, Japanese and Korean.

Think inside the box.

Free on the App Store for iPhone, iPad and iPhone Duo.

Download on theApp Store