Box Brain Sudoku
Today's puzzle
Sandwich sudoku
Classic rules, plus: a number outside the grid is the sum of the digits between the 1 and the 9 in that row or column.
00:00
Tap a cell, then a digit. Turn on Notes for pencil marks. Keyboard: arrows, 1–9, N for notes.
One puzzle a day in each mode Come back tomorrow for a new one, or get unlimited puzzles, hints and streaks in the app.
Stuck? The app's hints don't just reveal a digit: they point to where to look, name the technique, then show the move.
Sandwich sudoku puts numbers outside the grid. Each one is the sum of the digits sandwiched between the 1 and the 9 in its row or column.
All 12 modes
- Every row, column and 3×3 box holds 1 to 9 once each.
- Classic rules, plus: the digits in each dashed cage add up to its total, with no repeats in a cage.
- Rows and columns hold 1 to 9 once, and so does each thick-edged shape.
- Classic rules, plus: digits get bigger along each thermometer, from the bulb to the tip.
- Classic rules, plus: the digits along an arrow add up to the digit in its circle.
- Classic rules, plus: a number outside the grid is the sum of the digits between the 1 and the 9 in that row or column.
- Classic rules, plus: a white dot joins consecutive digits, a black dot joins a digit and its double. No dot means neither.
- Classic rules, plus: each sign points at the smaller of its two cells.
- Classic rules, plus: both long diagonals hold 1 to 9 once each.
- Classic rules, plus: the four shaded 3×3 areas hold 1 to 9 once each.
- Classic rules, plus: two cells a chess knight's move apart can't hold the same digit.
- Classic rules, plus: shaded squares hold even digits, circled cells hold odd digits.