The goal

Fill the 9×9 grid so every row, column, and 3×3 box contains 1–9 exactly once — classic sudoku rules. The twist: the grid is divided into outlined cages. The small number in each cage’s corner is the sum of its digits, and digits cannot repeat within a cage. Every puzzle has exactly one solution.

Entering numbers

• Select a cell by clicking or tapping; enter digits with the buttons below the grid or keys 1–9.
• Erase with the Erase button, Backspace, or 0; arrow keys move; Esc deselects.
• When all nine of a digit are placed, its button grays out.

Pencil marks (notes)

• Toggle pencil mode with ✏️ or P; digits become small candidate notes.
• Auto Candidate Mode fills empty cells with digits that don’t conflict in their row, column, or box (cage sums are up to you).

Tips

• Start with extreme cages: a 2-cell cage summing to 3 must be 1+2; a sum of 17 must be 8+9.
• The digits in any row, column, or box total 45 — compare against cage sums that fit (almost) inside to deduce single cells.

Finishing

The timer starts when the puzzle opens and stops when you solve it. When the grid is full, incorrect entries are highlighted so you can fix them. Easy has some starting digits; Medium and Hard start empty.