Kakuro
A crossword of sums: digits 1 to 9, none twice in a run.
Kakuro is a crossword with sums where the clues would be: the white cells take digits from 1 to 9, every run adds up to the number at its head, and no digit stands twice in a run. Here it is written the way a sudoku is — pick a cell, pick a digit, keep pencil marks if you like — and the board tells you only what your own digits already say: a digit its run already holds and a sum gone wrong turn red, a sum that is done turns grey. No hints, and nothing that checks you against the answer.
A new board every day — 6 × 6, 9 × 9, and 12 × 12 — the same for everybody, each with a single solution that reasoning alone reaches. No timer and no account needed: a board left half-done waits for you until the day turns, at midnight UTC.
Today’s boards
How to play
Fill the white cells with digits from 1 to 9 so that each run of cells — across or down — adds up to the number at its head.
A clue cell is cut by a diagonal: the number above it is the sum of the cells to its right, the number below it the sum of the cells beneath.
Within one run no digit appears twice.
Tap a white cell and pick a digit on the pad under the board; the same digit again clears it. With notes on, digits are pencilled small in the cell instead.
A reddish cell holds a digit its run already has, or sits in a run whose sum has gone wrong; a sum greys out once its run is done.
Beyond today’s board
No timer. Leave and come back — it’s saved.
Play today’s Kakuro