Murder sudoku: questions and answers

A logic puzzle drawn as the floor plan of a crime scene. You place every suspect so that no two share a row or a column, and the one person left alone with the victim is the killer. The explainer goes further.

No. Killer sudoku is a 9×9 number sudoku with cage sums. A murder sudoku has no numbers at all. See murder sudoku vs killer sudoku.

No. Only one rule carries over, one person per row and per column, and the clues are plain sentences.

Yes. Every case has exactly one solution, and our solver checks that you can reach it step by step without guessing before the case is published.

Yes, but by logic, not by hunch. The clues only say where people were. When the board is complete, whoever shared the victim's room is the murderer, however innocent they sound.

All cases are original. Our own engine builds them, grades them and proves each has one solution, and the settings and the cast of 24 suspects are drawn for the game.

Read each clue and cross out every cell it rules out. Place a person as soon as one cell is left, which closes their row and column for everyone else. Repeat until everyone is placed, then name the person in the victim's room. How to play walks through a full case.

Object and room clues, because they remove the most cells. "Not beside" clues remove the fewest, so leave them for last. More in reading clues.

No. Beside means directly above, below, left or right, and only cells in the same room count.

Any number, except in the victim's room. It holds the victim and exactly one other person: the killer.

The case goes cold. Reopen it, check your crosses and try again. Nothing is lost.

An Easy case takes two or three minutes. Hard cases take ten minutes or more, and Expert cases longer.

Cross out more before you place anything, scan each row for the only person who can reach it, and count who can still get into the victim's room. The difficulty and hints page has a full checklist.

Right here. Today's case is free in the browser, with no account and no ads.

At midnight UTC. Everyone in the world gets the same case on the same day, so you can compare times with friends.

The difficulty follows the week: Easy on Monday and Tuesday, Medium on Wednesday and Thursday, Hard on Friday and Sunday, and Expert on Saturday.

Yes. The archive keeps every past daily case. Each has a step-by-step solution once its day is over.

No. Open the page and play. There is nothing to sign up for.

Yes. Sudoku Murder: Cold Cases is on the App Store for iPhone and iPad and on Google Play for Android. See the app page.

Yes. The app is free to download and the daily case is free every day. The Detective Pass is optional.

Yes. The site and the app share one case a day, so your result is comparable wherever you play.

Yes. Sudoku Murder: Cold Cases is on Google Play for Android phones and tablets. See the app page.

English, Spanish, Dutch, German, Portuguese, Italian and French, on the site and in the app.

Yes. The printable page has sets of cases in Easy 5×5, Medium 6×6 and Hard 7×7, one case per page.

Yes. The solutions are at the end of each set, so you can check your work without spoiling the next case.

Yes. Print the daily page: the board and every clue are on it. Write each person's initial in their cell and cross out cells as you rule them out.