Murdoku Online is a free, independently run puzzle site built around one idea: a murder mystery you can actually solve with logic rather than a hunch. Every case hands you a floor plan, a cast of suspects, a victim and a column of witness statements. Your job is to work out where each person was standing when the lights went out. The suspect left alone with the victim is the murderer, and the answer is always provable — never a guess, never a coin flip.
The site went live as a small hand-built collection and now holds 142 public cases in six languages, alongside a daily case, a random-case generator, a full editor for building your own, and printable sheets for people who would rather solve on paper with a pencil. Everything on it is free, and nothing on it requires an account.
The original Murdoku concept is the work of Manuel Garand, and a widely played fan version was made by Dirk Aporius. This site is a further fan version: an independent reimplementation with its own engine, its own artwork and its own casebook, made because the idea deserved a home that worked properly on a phone, in more than one language, and without a download. It is not an official product, it is not affiliated with the original creators commercially, and it makes no claim on their work beyond the credit it gives them on every page.
A case obeys exactly two rules. First, each person occupies their own row and their own column — the victim included, so no two figures on the board ever share a line. Second, the room holding the victim contains exactly one suspect, and that suspect is the killer. Those two sentences generate an enormous amount of deduction. Because nobody shares a row or a column, two people can never stand directly beside one another; the only contact possible is diagonal. Because the board is square and holds one victim plus one fewer suspect than its width, placing anyone at all clears an entire row and an entire column for everybody else, and each placement cascades into the next.
This is the part that takes the work. A case is not a grid with some flavour text attached; it is a constraint system that has to have exactly one answer, and that answer has to be reachable by a human being reasoning forward.
Before any case is published, a search solver enumerates every legal arrangement of the cast on the floor plan and confirms that precisely one satisfies the whole clue list. Not “probably one” — the search is exhaustive. A case with two answers, or with none, never reaches the casebook.
Uniqueness on its own is not enough. A puzzle can have a single answer that is only findable by trying a possibility, following it to a contradiction and backing out. That is bookkeeping, not deduction, and it is miserable to do by hand. So a second engine solves each case the way a person would — purely forward, one justified elimination at a time, with no trial and error anywhere — and a case is accepted only if that engine gets all the way to the end. When you are stuck, the next step exists; it has simply not been spotted yet.
A statement you read, reason about and then discover was never needed is a small betrayal of the reader. Each clue in a case is therefore removed in turn and the case re-solved without it. If the case still falls out, the clue was padding and the candidate is rejected outright rather than patched. Measured before this rule was enforced, roughly one clue in six across the whole corpus was dispensable — in the hand-made cases just as often as in the generated ones.
Difficulty here is not a matter of exotic statements. A hard case keeps most of the board open long after you have read everything, forces you to hold several partial deductions at once, and resists giving up its first certain placement for a long stretch. Cases are rated on those properties — how much of the grid survives the full clue list, how many suspects the reasoning has to span at once, and how late the first placement lands — rather than on which kinds of statement happen to appear.
The interface, the clue texts and the case titles exist in German, English, Spanish, Portuguese, French and Dutch. They are written for each language rather than run through a translator: a witness statement has to read like something a person would say, and the crime-fiction register that makes a case title land in one language rarely survives a literal rendering into another. Case titles in particular are composed separately per language and checked for uniqueness across the entire casebook.
Murdoku Online is made and maintained by a single independent developer with a long habit of pencil-and-paper logic puzzles, working on it outside a day job. There is no company behind it and no team. The casebook is hand-curated: cases are drafted, run through the checks described above, played, and then either kept or thrown away. If you want to reach the person who made this, that is what support@murdokuonline.org is for, and the contact page says what to expect.
Hosting, the domain and the time all cost something, and the site has no subscription, no paywall and no shop. It is funded by advertising served through Google AdSense. Ads are kept out of the board, out of the clue column and out of the navigation, are labelled as advertising, and never sit where a mis-tap would cost you a placement. What the advertising stores on your device, and how to turn personalised advertising off, is set out in full in our privacy policy. We do not accept paid placements inside the case texts, and no case or review on this site has been paid for by anybody.
No account, ever — the puzzles work without knowing who you are, so the site does not ask. No streak to protect and no daily nagging. No case locked behind a payment. No interstitial you have to dismiss before you can read a clue. And no puzzle published that the engines above have not certified as having one answer, reachable by reasoning.