Murder mystery prompts for ChatGPT, Claude & Gemini
Updated
Whodunits and interrogations whose solution is sealed before you start — the culprit can't change mid-game, and you check the seal after. Free, no signup. Each game is a ready-to-play prompt (we call it a game card) that you open in your own AI assistant.
A sealed mystery is a whodunit whose solution is committed as a SHA-256 hash before the game ships. The culprit, the method and the evidence are fixed in a file on this site, so the assistant is refereeing a case that already has an answer instead of deciding who did it once you accuse someone.
New to AI games? Read AI murder mystery games that can't cheat.
| Game | What it is | Players | Length | Ages |
|---|---|---|---|---|
| Blackfile №1: The Vanishing at Larchmont Hall | A 1925 locked-room whodunit: an heiress bolts a glass conservatory from the inside and is not there when the doors come down. | 1 | 60–90m | 12+ |
| Blackfile №2: A Death at the Wyke Hydro | A snowbound 1929 poisoning whodunit: six suspects, one cup of hot milk, and an answer sealed before you start. | 1 | 75–105m | 12+ |
| Blackfile №3: The Long Exposure at Harrowfell | A 1953 observatory whodunit: a death on the dome stair, six suspects who cannot leave the fell, twenty moves, and a culprit sealed before you start. | 1 | 60–90m | 12+ |
| The Third Carol: A Christmas Murder Mystery Game | A Christmas murder mystery game for one to eight at one screen: six suspects whose every answer and every lie were written and sealed before play, four rounds of evidence, and one accusation you can check against that file afterwards. | 1-8 | 60–90m | 12+ |
| Under Caution: An Interrogation Game | A ready-made ChatGPT detective game prompt: you cite a statement line or an answer against an exhibit, and a list sealed before play decides each citation, so you can check each one afterwards. | 1 | 25–45m | 12+ |
| No Ghost Speaks: A Halloween Murder Mystery Game | A Halloween murder mystery game for 12 and over, one to eight at one screen: every answer and lie sealed before play, one accusation to check after. | 1-8 | 45–75m | 12+ |
Can ChatGPT run a murder mystery without cheating?
The failure mode of playing detective with an assistant is that it wants you to be right. Accuse the gardener and the gardener becomes guilty; the clues you half-remember get retrofitted into a confession. Nothing was decided in advance, so nothing can contradict you.
Every case on this shelf is written solution-first: the Blackfile cases, which you investigate alone, The Third Carol, a Christmas murder mystery game for a table of up to eight at one screen, where the assistant plays all six suspects; No Ghost Speaks, its Halloween counterpart, where five sheeted supper guests answer only from sealed lines and you break their lies with numbered exhibits; and Under Caution, an interrogation game in which you break a suspect's signed statement with numbered exhibits. The full answer and a random salt live in a reveal file whose SHA-256 hash is published before release. The card tells the assistant to fetch that file and referee against it, and every alibi, timetable and lie you are told comes out of a document that existed before you opened the chat.
When you finish, you read the reveal and paste it into /verify/ with the published hash. Your browser recomputes the digest. If it matches, the solution you just read is provably the one committed before you played — change a single character of it and the seal shows broken. The case cannot have moved to fit your guess, because a hash of a moved case is a different hash.
Questions about murder mysteries
How do I know the AI is not just making the answer up?
Because the answer was hashed before the game was published, and you check that hash yourself. After the reveal, paste the solution text and its salt into /verify/ along with the published commitment. Your browser recomputes SHA-256 locally and tells you whether it matches. A retrofitted solution produces a different digest, so the seal breaking is the tell.
Are the cases actually solvable, or do they need a leap?
Each case is checked cold before it ships: the culprit is uniquely determined by the evidence available to you, and every innocent suspect is excluded on at least two independent grounds. That check is part of the build, not a claim about intent — a case where two suspects both fit, or where the answer needs information you were never given, does not ship.
Can I replay a sealed mystery?
The solution is fixed, so a second run of the same case is a re-read rather than a new mystery — worth doing to see the clues you walked past, not to be surprised again. The Blackfile cases, The Third Carol, No Ghost Speaks and Under Caution's three interviews have unrelated solutions, and the social deduction and duel shelves use the same sealing method on setups that are hidden rather than deduced.
If you like murder mysteries
- Social deduction games
Find the liar among NPCs your AI plays, with a committed setup you can verify.
- Logic puzzles
Deduction with one provable answer, sealed before release — the AI checks your reasoning instead of grading it kindly.
- Escape rooms
Locked rooms you read your way out of before the timer — the final code sealed so the room can't move it.