Kakuro

Overview

Kakuro is a numerical crossword built from intersecting sums. Each white square receives a digit from one to nine. A clue before a horizontal or vertical run gives the sum of the digits in that run, and no digit may repeat within the same run. A cell usually participates in both an across sum and a down sum, so its value must satisfy both simultaneously. Black clue cells separate runs; there are no Sudoku boxes or requirement to use every digit in a whole row. This local pzpr implementation starts with one introductory five-by-five board. A practice selector offers rotations and reflections of that same board, explicitly labelled as orientations rather than separate authored levels or an endless puzzle generator.

How to Play

Select a white answer square and type a digit, or use the on-screen number buttons. On a phone, tap the square before choosing the digit. Use the erase button to remove an entry and Undo to reverse your latest action. Read the diagonal clue cell carefully to identify its across and down sums. Press Check answer when you want feedback about the current arrangement. Restart clears your answers on the selected orientation. Changing the practice orientation also starts a clean attempt on the transformed introductory board.

Tips & Strategy

Start with short runs whose target admits very few distinct-digit combinations. A two-cell sum of three must use one and two, while a two-cell sum of seventeen uses eight and nine. Intersect those candidate sets with the perpendicular run to determine order. Remember that a valid sum with a repeated digit is still invalid. Track combinations for the whole run instead of placing numbers independently until the total happens to match. When checking an error, inspect both sums through the selected cell. Rotated practice boards preserve the same underlying puzzle, so use them to practise reading clue directions rather than expecting new logical content.

About this version

Kakuro uses the locally built kakuro rules from pzprjs. The original authors retain credit under the MIT license. SonoTap provides the browser adaptation and this guide.