Killer Sudoku

Row constraint: each row must contain 1–9 exactly once
Column constraint: each column must contain 1–9 exactly once
Box constraint: each 3×3 box must contain 1–9 exactly once

⚔️ In battle Round {round}/{total} 5:00 0 : 0

📖 Killer Sudoku Rules

Fill the 9×9 grid with digits 1–9 so that no digit repeats in any row, column or 3×3 box.

Cells are grouped into dashed-line "cages"; each cage shows a target sum in its top-left corner
The digits in a cage must add up exactly to its target sum
Digits within a cage cannot repeat (even across rows, columns or boxes)
A cage may span multiple rows, columns or boxes

Start with single-cell cages: the cell equals its target sum
Use combination exclusion: two cells summing to 3 can only be 1+2; summing to 17 can only be 8+9
Cross-analyze rows, columns and boxes: combine standard and cage constraints to narrow candidates
Use the "45 rule": each row/column/box sums to 45, which helps deduce cage boundaries
Note mode: use ✏️ notes to mark each cell's candidates and aid reasoning

Invite a friend for real-time battles! Take turns filling digits — correct moves keep your turn, mistakes pass it. First to finish wins.