Kakuro Game

Kakuro — sometimes called "cross sums" — originated in Japan and became popular worldwide as a demanding but accessible number-logic game. The grid looks like a crossword: black cells separate the white playable cells, and each black cell contains up to two triangular clue compartments.

The two rules: Every run of white cells (a sequence going across or down) must sum to the number shown in the clue, and no digit may appear more than once within that run. Those two constraints — sum and uniqueness — are all the rules. Everything else follows from logic.

Why it is satisfying: Unlike puzzles that allow trial and error, a well-constructed Kakuro game has one solution that falls out of pure deduction. Each move you make reveals new constraints that unlock further moves. The feeling of a chain of forced deductions clicking into place is what keeps solvers coming back.

New to the game? The rules page walks through grid notation and the first deduction technique in under five minutes. The beginner guide then covers a complete solving approach from first principles.

Open freekakuro.com in any modern browser. A puzzle loads immediately at medium difficulty. Use the controls to change difficulty before generating a new game.

Reading clues: Each black cell contains one or two numbers in triangular compartments. The upper-right number is the across-run clue; the lower-left number is the down-run clue. White cells in that run must sum to the clue, using each digit 1–9 at most once.

Placing digits: Click or tap a white cell, then type a digit or tap the on-screen number pad. Cells with constraint violations turn red. Correct placements remain neutral until the puzzle is complete.

Using candidates: Enable the candidate overlay to show a 3×3 mini-grid inside each empty cell. Click individual digit positions to mark or unmark them as you eliminate possibilities through logical deduction.

Stuck? The combination reference lists every valid digit set for each sum and run length. For strategy beyond forced moves, the technique library covers intersection logic, residual sums, and naked pairs.

Kakuro and Sudoku are both number-logic games solved by deduction, and the skills overlap: both reward systematic candidate elimination and careful constraint tracking. But they are fundamentally different puzzles.

Sudoku has a fixed 9×9 grid with nine fixed boxes. Its constraint is that each row, column, and box contains the digits 1–9 exactly once — there is no arithmetic. Kakuro has a variable-shape grid with no fixed structure. Its constraints are sum-based: each run must hit an exact total, and no digit repeats within a run.

In practice, Kakuro demands more active arithmetic thinking. Before placing a digit you must consider which combinations of digits sum to the run's clue, then intersect that with the constraints from crossing runs. The combination reference and the helper calculator are specifically designed to make that arithmetic fast.

Experienced Sudoku solvers typically find Kakuro accessible but rewarding — the logic feels familiar but the puzzle demands a new set of pattern-recognition skills.