Killer Sudoku
A sudoku with no digits given: only cages, and the sums they must make.
Killer Sudoku is a sudoku with no digits given: the grid is cut into dashed cages instead, each with the sum its digits must make, and no digit repeats inside a cage. Here it is written the way a sudoku is — pick a cell, pick a digit, keep pencil marks if you like, and look under the pad for the selected cage’s combinations and a calculator for adding up sums — and the board tells you only what your own digits already say: a digit that repeats in its row, column, box or cage turns red, and so does a cage gone wrong; a cage that is done greys its sum and outline. No hints, and nothing that checks you against the answer.
A new board every day — Gentle, Steady, and Tricky — 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
On paper
A PDF of today’s board at each level, new every day: A4, black and white, with how to play on the last page. Free, no sign-up.
How to play
Fill the grid so every row, every column and every 3 × 3 box holds the digits 1–9, each exactly once.
The dashed outlines are cages: the digits in a cage add up to the small number in its corner, and no digit repeats within a cage.
No digit is given. The sums are enough: there is exactly one solution, and it never needs a guess.
Tap a 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. Under the pad: the selected cage’s combinations, and a calculator for adding up sums.
A reddish cell holds a digit its row, column, box or cage already has, or sits in a cage whose sum has gone wrong; a cage’s sum and outline grey out once it is done.
No timer. Leave and come back — it’s saved.
Play today’s Killer Sudoku