Dedoku

Dedoku is a detective logic puzzle built around a simple Sudoku-style restriction: every witness and the missing item must occupy a different row and a different column. Instead of numbers, you investigate a floor plan filled with rooms, furniture, usable surfaces and witness statements.

The name joins deduction with Sudoku, but the experience is closer to opening a mystery dossier than filling a number grid. A clue may place someone in the Library, north of a display case, beside a chair or alone in a room. Your job is to translate each sentence into possible and impossible squares.

The final case piece is the missing treasure—a diamond, crown, compass, ruby, trophy or golden key. When every case piece has one proven position, the solution identifies who found that item and where.

The four rules behind every case

1. 01

   Read the case file

   Select each witness or item card and identify the rooms, directions, objects or traits mentioned in its clues.

2. 02

   Mark possible squares

   Use Smart or Note mode to record every square still compatible with that case piece.

3. 03

   Apply the line rule

   When a row or column is claimed, remove it from every other witness and from the missing item.

4. 04

   Place every case piece

   Combine the clue restrictions until each witness and item has one square, then check the complete case.

One case piece in each row

A witness or missing item claims its entire row when placed. Every other case piece can be crossed out of that row. You are not required to fill every square; most squares remain ordinary rooms and furniture after the investigation is complete.

One case piece in each column

Columns work exactly the same way. The interaction between row and column claims creates Dedoku’s Sudoku-like backbone. If all remaining possibilities for one witness lie in a single row, that row is effectively reserved even before the exact square is known.

Only valid floor and surfaces can hold pieces

People may stand on normal floor or usable objects such as a chair, rug, sofa, stool or bench. Solid props—including shelves, statues, display cases and plants—block their squares. The object record beside the map shows which illustrated furniture is usable and which is blocking.

Every statement must still be true

A complete arrangement is not correct merely because its rows and columns do not clash. Room, direction, adjacency, trait and count clues must all agree. Use Check when you want the case engine to compare your current placements with the verified answer.

How to mark the online Dedoku map

Select a witness card in the case file, then tap squares on the building map. The selected portrait and active card show whose evidence you are recording. On desktop, the complete tool desk sits beside the board. On a phone, the most-used marking controls remain above the map while case actions and the object record move into the More menu.

Solve asks the human-style logic engine to complete what it can and then fills the verified answer if its current deduction rules cannot finish the trail. New Case generates a different building, item, witnesses and clue set at the chosen difficulty.

How to read Dedoku clue language

The case cards use several families of evidence. Direct clues are the best starting points; relational clues become stronger after another witness has been narrowed.

Choose the depth of the investigation

Difficulty combines map size with clue style. A larger building provides more positions, while indirect evidence makes you carry possibilities through a longer chain before a placement becomes certain.

Field strategy for difficult cases

• Start with named places. A room, object, row or column usually produces the smallest first set of squares.
• Pencil every surviving square. Incomplete notes hide line locks and make later clues harder to apply.
• Claim lines before exact cells. If a witness has three possibilities in one row, no other case piece may use that row.
• Revisit relational statements. “North of Maya” becomes much stronger after Maya is restricted to two squares.
• Distinguish a prop from a surface. A chair may be a legal position while a display case blocks its cell entirely.
• Count people, not pieces. A room-total clue generally ignores the missing item unless the clue names it.
• Use contradictions carefully. If a trial position forces two pieces into one column, that position is impossible—but keep the reasoning visible in your notes.
• Verify the complete file. The final layout must satisfy every clue, not simply place the treasure convincingly.

How fresh Dedoku cases stay fair

The generator assembles a building layout, room themes, objects, character portraits, a missing item and a hidden solution. It then creates a larger pool of possible clues and chooses enough evidence to leave one valid arrangement. A uniqueness solver rejects a case if a second answer remains.

A separate human-style solver grades how the case can be progressed through recognisable deductions. That check helps difficulty describe the reasoning trail rather than only the dimensions of the map. Generation runs in a same-origin Web Worker so the interface can show the case-file animation while the logic is checked away from the main page.

The four building themes—Mystery Mansion, Grand Hotel, Moonlight Museum and Puzzle Castle—change the room floors and furniture, while the six missing items and varied witness groups keep the story fresh. The crimes remain light and family-friendly: something valuable has disappeared, and careful reasoning recovers it.