Detective Sudoku: How to Play + 100 Free Levels
Detective sudoku swaps digits for suspects: one clue per row and column, a room-based grid, and a killer hiding in plain sight. EveryClue's free Crime Scene mode ships 100 levels across five difficulty tiers, from a 6×6 starter board to a 9×9 expert case — no signup, no timer pressure unless you want one.
What is detective sudoku?
Detective sudoku is a logic-grid game that borrows sudoku's core constraint — exactly one answer per row and exactly one per column — and replaces digits with suspects on a floor plan. Instead of filling numbers 1 through 9, you place every character in a crime scene onto a grid divided into rooms, using clues about who was where, then work out who was alone with the victim. EveryClue's Crime Scene mode is a free, 100-level implementation of this format: no signup, no paywall, and a fresh floor plan every level instead of a repeating template.
If you searched "detective sudoku," "murder mystery sudoku," or "sudoku detective game," the short answer is: play Crime Scene — it is exactly that, with 100 free levels split across five difficulty tiers, playable in 8 languages, with a per-level leaderboard for players who want to race the clock.
The format sits at an intersection of three things puzzle fans already know separately: sudoku's row-and-column constraint, the room-based floor plans of a classic country-house murder mystery, and the deduction habit that whodunit-grid and logic-grid players already have. If any of those three appeal to you individually, detective sudoku is worth trying — it doesn't require prior experience with any of them, since every clue in Crime Scene is a plain sentence, not a symbol or a pre-filled digit.
Why the row/column rule works here
Sudoku's uniqueness constraint is popular because it's simple to state and hard to fully exploit at a glance — you always know the rule, but applying it to a specific board still takes work. Detective sudoku keeps that exact property. Once you know "one suspect per row, one per column," a clue like a suspect being "exactly 3 columns east of" a named suspect becomes a hard spatial constraint you can test against every open cell, not a vague hint.
The room layer adds a second constraint on top of the grid one. A suspect who "was beside a cash register" or "was sitting in a chair" is anchored to a specific piece of furniture, which usually exists in only one room — so an object clue and a room clue often solve each other simultaneously. This is why Crime Scene's harder tiers lean on relational clues (same row, same column, offset-by-N, alone-with) rather than simply making boards bigger: a bigger board with only direct clues would be tedious, not harder in an interesting way.
How to play
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1. One suspect per row, one per column
Just like sudoku's row/column uniqueness rule, every row and every column of the board holds exactly one character. A clue like "Amelia was in row 2" or "Bram was in the first column" pins that person to an exact strip of the grid before you even look at the room layout.
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2. Rooms carve the board into walled sections
The grid is also divided into rooms — a Waiting Area, a Garage, a Study, a Kitchen, and so on — each covering a cluster of cells. Room clues read like "Dmitri was alone in the Study" or "Fiona was in the Kitchen," narrowing a suspect to one room before you pin their exact cell.
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3. Furniture clues narrow it further
Once a room is set, object clues close the gap. Real examples from the game: a suspect "was beside a cash register," another "was sitting in a chair," another "was exactly 3 columns east of" a named suspect. Relational clues like same-row, same-column, and offset-by-N connect two suspects at once, so solving them together is faster than solving them in isolation.
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4. Accuse the suspect alone with the victim
Once every clue checks out and every suspect has a cell, the win condition is the same on every level: find who was alone with the victim's room, and accuse them. A wrong accusation doesn't end the level — you can re-check the board and try again.
Crime Scene vs. other logic-deduction games
Detective sudoku, classic sudoku, logic-grid whodunits, and print-format murder-scene placement puzzles all reward the same elimination instinct, but they differ in format, cost, and how the story is told. Here's an honest comparison — no category wins on every axis.
| Format | Constraint | Story layer | Cost |
|---|---|---|---|
| Crime Scene (EveryClue) | One suspect per row/column, plus room and furniture clues | Named suspects, rooms, and a murder to solve | Free, 100 levels, no signup |
| Classic sudoku | One digit 1–9 per row, column, and 3×3 box | None — pure number placement | Usually free, near-infinite generators |
| Logic-grid whodunits | Attribute matrix (suspect × weapon × room × motive) | Suspects and motives, no spatial board | Varies; EveryClue's own whodunit grid is free daily |
| Murdoku-style print puzzles | Row/column placement close to Crime Scene's rule set | Illustrated murder scenes, book-format delivery | Usually paid (book or bundle) |
If you like that print-puzzle row/column placement rule but want a free, browser-based version with a leaderboard and no book to buy, Crime Scene is the closer match. If you want a story-free number grid, classic sudoku is still the fastest way to get one. If you prefer an attribute matrix with no spatial board at all, EveryClue's own whodunit puzzles cover that format daily.
Start by difficulty tier
All 100 levels are unlocked from the start — there's no forced progression. Jump straight to the tier that matches your experience:
Frequently asked
Is Crime Scene detective sudoku free to play? +
Yes. All 100 levels are free, with no signup required to play. Creating a detective name is optional and only needed if you want your solve time saved to a level's leaderboard.
How many levels are there? +
100 fixed levels, grouped into five difficulty tiers of 20 levels each: Very easy, Easy, Medium, Hard, and Expert. Every level is open from the start — nothing is locked behind progression.
How hard does it get? +
Very easy and Easy levels use a 6×6 board with four to six rooms. Medium steps up to 6×6–7×7 boards. Hard and Expert levels grow to 7×7 through 9×9 boards with more rooms, more furniture clues, and a higher share of relational clues (same row, same column, offset-by-N, alone-with) that connect two suspects at once instead of pinning one directly. In practice this means Very easy levels can usually be solved from direct clues alone, while Expert levels expect you to chain two or three relational clues before a cell becomes certain.
Does it work on mobile? +
Yes. The board is tap-to-place on touch screens and click-to-place on desktop — no drag-and-drop required.
What languages does it support? +
All 100 levels are playable in 8 languages: English, Spanish, Portuguese, Japanese, French, German, Korean, and Chinese. Clue sentences, room names, and suspect names are localized, not machine-translated at render time.
Do I need an account to play? +
No account is required to solve any level. You only need a detective name (freely editable, defaults to an anonymous handle) if you want your time to appear on that level's leaderboard.
How do the leaderboards work? +
Every level has its own solve-time leaderboard, ranked by fastest completion. Submitting a leaderboard time also tracks your mistake count and hints used, but ranking is by time only.
What's the win condition? +
Place every suspect on the board so all of their clues are satisfied, then accuse the one suspect who was alone with the victim's room at the moment of the murder. A wrong accusation doesn't end the level — you can try again. The game will not let you submit while any clue is still in conflict, so a completed board is always internally consistent before you're asked to accuse anyone.
Can I replay a level after solving it? +
Yes. Every level stays open after you solve it, so you can replay it to try beating your own best time, and your solved-state is remembered per browser so completed levels show a checkmark on the level-select screen.
More on EveryClue
Prefer an attribute-matrix puzzle instead of a spatial board? Read about whodunit puzzles, or see how Crime Scene compares to games like Murdle. Short on time? The 5-minute mysteries hub covers EveryClue's quickest cases, and daily puzzles like Wordle explains the daily-ritual format the whole site is built around. For a broader view of the genre, see online murder mystery games.
For background reading: What Is a Whodunit Puzzle? covers the genre's mechanics and history, How to Play a Whodunit Grid is a beginner walkthrough for EveryClue's other deduction format, and Lateral Thinking Puzzles explains the yes/no mystery format if you want a change of pace from grid logic. You can also browse the case archive, check the global leaderboard, or jump straight back into Crime Scene.
Online murder mystery games 
5-minute mysteries 
Sherlock Holmes Pack