A number crossword that plays fair.
Kakuro by Splash Logic. We prove every puzzle can be solved by logic alone. No guessing, ever. Try the corner of a real board below.
The left column adds to 3 and can't repeat a digit, so it must be 1 and 2.
Every puzzle can be solved by logic, never by guessing
We check every puzzle twice before it ships: it has exactly one answer, and you can reach that answer by logic, from the first square to the last. If you get stuck, the answer is still on the board.
The two empty squares in this column can only be 2 and 6, in some order, so no other square in the column can hold either digit.
Hints that explain why
A hint names the technique and the exact lines it applies to. You learn something you can reuse, instead of just watching a square fill in.
Learn one technique at a time
Seven named techniques, taught in order from beginner to expert boards. Each one builds on the last.
See all seven techniques →The whole board, always in view
Boards run from 5×5 to 9×9. No zooming and no scrolling. You always see the whole puzzle at once.
A daily puzzle, with a streak
Easy on Monday, hard by Sunday. Come back each day and keep your streak going.
No clock while you play
Play at your own pace. Puzzles on the main path are never timed. The daily puzzle shows a par time, if you like something to beat.
From the app
Questions
What is Kakuro?
A number crossword, also called cross sums. You fill white squares with digits 1–9 so each line adds up to its clue, with no digit repeated in that line.
Is it hard?
The rules take a minute to learn. Getting good takes a handful of named techniques, which the app teaches one at a time.
Do I need to be good at maths?
No. You are only ever adding small numbers, and the app shows you which combinations are possible.
How is it different from Sudoku?
Sudoku fills a fixed grid by position. Kakuro's clues are sums, so every line is its own small addition puzzle.
Is it free?
Yes. Kakuro will be free to play on Android.
When is iOS coming?
Android comes first. There is no date for iOS yet.