How to play Murdoku-style puzzles

By Alejandro Portillo Guerrero · Updated October 2026 · 8 min read

A Murdoku-style puzzle — also called murder sudoku — is a logic puzzle that puts a whodunit on a sudoku grid. You place suspects on a floor plan so that no two share a row or a column, use written clues to rule out every other arrangement, and the one suspect left in the victim's room is the murderer.

No numbers, no arithmetic, no guessing. Below: the rules as they work on this site, every clue type, a small worked case, and the habits that make hard cases feel easy.

What is a Murdoku-style puzzle?

Take the core rule of sudoku — every row and every column gets exactly one of something — and swap the digits for people. Then draw a manor floor plan over the grid: a Study, a Library, a Kitchen, a Hall. Somewhere on that plan lies the victim.

Each case gives you a list of suspects and a handful of clues: "Poppy stood beside the armchair." "Basil was not in the Kitchen." On their own the clues look thin. Combined with the row-and-column rule, they leave exactly one way to place everyone — and then exactly one suspect shares a room with the victim. You never pick a culprit on a hunch. The logic corners them.

The rules

1. One suspect per row and per column

No two suspects share a row or a column. A 6×6 case has six suspects, so every row and every column ends up with exactly one person in it.

2. Rooms matter, but they don't have a limit

Thick lines divide the grid into rooms. A room can hold several suspects or none — only rows and columns are limited. Rooms exist for the clues and for the final reveal.

3. Furniture and the victim block their cells

Nobody can stand on the victim or on a piece of furniture like an armchair or a stove. Those cells still belong to their row and column, though: a row with the victim in it still needs a suspect somewhere else in that row. Rugs are just floor — suspects stand on rugs all the time.

4. "Beside" never goes through a wall

"Beside" means directly up, down, left or right — never diagonal. And every room edge is a wall, so two cells are only beside each other if they touch and sit in the same room. A suspect in the Study is never "beside" anything in the Kitchen, even when the cells touch on the grid.

5. The suspect in the victim's room is the murderer

When every suspect is placed and every clue holds, exactly one suspect is in the same room as the victim. Name them and the case is closed.

The clues you'll meet

Clues on murdersudoku.com always use the same wording, so it pays to know exactly what each one means:

• "X was in the Library." / "X was not in the Library." — X's cell is (or isn't) one of the Library's cells.
• "X and Y shared a room." — both stand somewhere in the same room. They don't have to touch.
• "X was beside Y." / "X stood beside the armchair." — orthogonal neighbours, in the same room.
• "X was directly above Y." (or below, left of, right of) — the exact neighbouring cell in that direction, again with no wall between.
• "X was right next to the Kitchen." — X is not in the Kitchen but stands on a cell that touches it. This one is about location, so walls don't matter.
• "X was in the same row as the stove." (or column) — just the row or column. Distance and rooms don't matter.
• "X stood in a corner of the manor." — one of the four corner cells of the whole grid.
• "X stood in a corner of the Hall." — X is in the Hall, on a cell where the room's outline turns: there is a wall or the edge of the board on one side above or below, and on one side left or right.

Worked example: the Case of the Quiet Library

Here is a small case made for this guide (not a daily puzzle, so no spoilers): four suspects on a 4×4 manor. Columns run A to D and rows 1 to 4, so "C1" is column C, row 1.

The floor plan: the Study fills A1, B1, A2 and A3. The Library runs down the right edge (C1, D1, D2, D3, D4), and the victim lies in C1. The Hall is the middle block (B2, C2, B3, C3) plus C4. The Kitchen is A4 and B4, with an armchair in A4.

The suspects are Vivian, Basil, Poppy and The Colonel. The clues:

1. Vivian stood in a corner of the manor.
2. Poppy stood beside the armchair.
3. Basil stood in a corner of the Hall.
4. The Colonel was not in the Study.

Try it yourself first if you like. Here's the solve.

Step 1: Read the board

Two cells are off-limits: the victim in C1 and the armchair in A4. The manor's corners are A1, D1, A4 and D4, but A4 holds the armchair, so Vivian (clue 1) must be in A1, D1 or D4. Not enough yet.

Step 2: Use the wall rule on Poppy

The armchair in A4 touches two cells on the grid: A3 above it and B4 to its right. But A3 is in the Study and the armchair is in the Kitchen, so there's a wall between them. That leaves one cell: Poppy is in B4. Row 4 and column B are now closed to everyone else.

Step 3: Find Basil's corner

Which Hall cells are corners of the Hall? B2, C2, B3 and C4. (C3 isn't: the Hall continues both above it and below it, so the outline doesn't turn there.) B2 and B3 sit in column B, and C4 sits in row 4 — both taken by Poppy. Basil is in C2.

Step 4: Let the last clue decide

Vivian's corners are down to A1 and D1, since D4 is in Poppy's row. The free rows are 1 and 3, the free columns A and D. If Vivian took D1, The Colonel would be forced into A3 — and A3 is in the Study, which clue 4 forbids. So Vivian is in A1 and The Colonel is in D3.

Step 5: Name the murderer

The victim is in the Library, and the only suspect in the Library is The Colonel, in D3.

Every clue was needed: drop any one and more than one arrangement fits. Real cases work the same way, just bigger.

Solving tips

• Start with the tightest clue. A manor corner, a piece of furniture or a single small room leaves only a few cells. "X was beside Y" usually only helps once one of them is placed.
• Cross out before you place. Use pencil marks to eliminate cells: blocked cells, used rows and columns, rooms a clue rules out. Most of the solve is elimination.
• Scan rows and columns, not just suspects. A row with only one usable cell left is as forced as a suspect with one cell left.
• Re-read every clue after each placement. A clue that allowed six cells at the start may allow one now.
• Check the walls when a clue seems impossible. If an adjacency can't work, you've probably counted a neighbour across a room edge, or a diagonal.
• Test a "what if" to the end. In step 4, assuming Vivian was in D1 led straight to a broken clue. Following an assumption to a contradiction is logic, not guessing.

Common mistakes

• Counting diagonals, or reaching across a wall, as "beside." Neither ever counts.
• Treating "right next to the Kitchen" like "beside." It ignores walls and means X stands outside the Kitchen, touching it.
• Forgetting that blocked cells keep their row. The victim's row still needs a suspect.
• Assuming one suspect per room. Only rows and columns are limited.

Easy, medium and hard

The daily case comes in three sizes: Easy is a 5×5 manor with five suspects, Medium is 6×6 with six, and Hard is 7×7 with seven, fewer clues per suspect and longer chains of deduction. Every case has exactly one solution.

Where to play free

• Today's daily case — in your browser, free, no sign-up, the same board for everyone.
• Printable cases — today's three cases on paper or as a PDF; check your answer online.
• The Cozy Culprits app — our free app for iPhone and Android. It builds the daily on your phone, so it plays offline, and it adds a full casebook, streaks and leaderboards.

Want more depth? The Cozy Culprits guides cover how to play murder sudoku with illustrated rules, an honest comparison of Murdoku and Cozy Culprits, and more puzzle guides.

A note on the name "Murdoku"

"Murdoku" is the name of Manuel Garand's puzzle book series. This site is not affiliated with it. We use the word here to describe the puzzle style that many people search for by that name: sudoku-style placement with a murder mystery on top. Murder Sudoku and Cozy Culprits are our own puzzles, with the rules described above.

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