You start with Envelope 1: fourteen documents. Reports, statements, photographs, phone records, a map. Read everything. Pin what matters. Nothing is decorative; every document was written to be cross-referenced with another.
Every case has three objectives in a fixed order, the way a real reinvestigation would run: clear the wrong man, establish the means, name the killer. Type your answer. It is checked on our server, so there is no answer key to peek at.
A correct answer opens the next envelope: four more documents nobody in the original investigation looked at. The timeline fills in. The last envelope is the solution file, written as the cold-case unit would write it.
Alone, your progress saves on your device. With friends, open a room and share a 5-letter code. Everyone reads on their own phone; objectives, pins and notes stay in sync for three hours (the host can extend). Up to eight detectives. Guests never pay.
Three hints per objective, from a gentle nudge to the answer. Using a hint does not lock anything or change your result. There is no timer.