How to play an online cold case file

1. What you are given

A case file is a folder of 20 to 30 documents sorted the way a real one is: Police Reports (incident report, scene report and sketch, evidence log, the original detective's summary and the cold case unit's reopening memo), Forensics (autopsy, laboratory reports), Witness Statements (the suspects and the people around them, in their own words), Photographs (scene frames and a persons-of-interest sheet), Records (phone company responses, logs, receipts, patrol reports, alibi checks), Personal Documents (letters, memos, contracts) and Press (a feature written decades later).

Nothing in the folder is marked as important. There are no detective's notes, no bold passages, no links from one page to another. Documents that matter look exactly like documents that do not. That is deliberate, and it is the reason the game is hard.

2. How to read it

Statements are what people say. Records are what happened. Every suspect gives an account of the night. Somewhere in the records folder is a document, written by a stranger with no reason to lie, that either supports that account or breaks it. Your job is to test every statement against every record.

• Write down every time. A phone company log, a transmitter log, a scale ticket and a patrol log may each carry one timestamp that matters.
• Write down every claim of location. Who says they were where, and which document written by someone else agrees?
• Notice what witnesses say about each other in passing. People reveal more about others than about themselves.
• Notice what is missing. An object that should be in the room, a letter that should be in the box, a log entry that should not exist.

Standard of the cold case unit: a conclusion must rest on at least two independent documents. A statement is not a record. An alibi that nobody checked is not an alibi.

3. The two-source rule

Every case on this site is written so that the killer is contradicted by at least two independent documents, and every innocent suspect is cleared by a specific record, not by absence of evidence. If your theory rests on one document, on a motive alone, or on the person who "seems off", it is wrong. When two records agree with each other and disagree with a statement, you have found it.

4. Accuse

Press Accuse and choose a name. You get one attempt and the button asks you to confirm. Whether you are right or wrong, the case closes and a Solution folder appears with the killer, the weapon, the motive and the sequence of events, citing every document that proves each point. Read it against your notes. Most players who get it wrong find they had already opened the document that would have told them.

5. Playing with friends: rooms of up to six

Press play on any case and choose Create a room. You will be asked for a first name and given a six-letter code and an invite link. Friends open the same case on their own phones, choose Join, and enter the code. Up to six people can be in a room, host included, and guests play the host's cases free.

• Everyone reads the whole file. Beside each document you see the initials of the room members who have already opened it, so you can split the folders and know who has covered what.
• Votes are secret. Each player accuses privately. Nobody sees the tally until the host presses Reveal, and then the case closes for the whole room at once and the solution opens on every phone.
• Talk out loud. The room is for reading and voting; the argument happens across the table, on a call or in your group chat. Two to three hours is typical for a group of four.

6. On a phone

Folders open as a list; each document opens full screen with zoom and next/previous buttons. Tables scroll sideways. Your place is saved on the device, so you can read the autopsy on the bus and the phone records at home.

Open the free case