Solo
Most of our customers play solo. A long evening, a drink, a clear table. Work the papers at your own pace. Some people read front-to-back; others scatter everything out at once and follow trails. Either works.
The full explanation From post box to verdict
How a Cosykiller
case works.
No app. No download. No dice. Just a box of paper, a sealed answer, and as much time as you care to give it.
Step one
What arrives on your doorstep
A hand-packed box, posted in padded brown paper. Inside, the contents of a fictional case file — the letters, photographs, telegrams, newspaper cuttings, maps and personal effects that the investigating officer thought worth keeping.
Every box is different. Every box contains enough material to solve the murder it documents. You'll also find a short introduction — a page or two of setup that orients you in the period, tells you who's who, and lays out the only rules we insist on:
- 1. Read everything in the order you prefer.
- 2. Take notes. It helps.
- 3. Don't break the final seal until you think you know the answer.
Step two
Three ways to work a case
However many investigators are around the table — and whether that's one, three, or four — the case bends to you, not the other way around.
With others
Two to four players is the sweet spot. Divide the paperwork — one takes the correspondence, another the maps, another the photographs — and reconvene every hour with theories. By the end you'll all be reading everything.
Pausing
Cases don't have a clock. Put the lid back on whenever you like. Come back next weekend, next month, next year. Nothing expires. The case waits.
Step three
The puzzles inside
Every case includes at least a few puzzles — simple ciphers, substitution codes, fold-marked maps, photographs that reveal something when paired.
The techniques are all taught inside the box, so you don't need to have done any of this before.
Cosy cases
Lean light on puzzles and heavy on reading. Ideal for a first case or a quiet Sunday.
Devilish cases
Assume you're willing to get a notebook out. Layered ciphers, nested clues, long evenings.
The reveal
Break the final seal
when you think you've got it.
When you think you know who did it — and why — open the final envelope. Inside you'll find a short narrative of the correct solution, a page of "things most people missed," and a note from the author.
If you got it wrong, it's still satisfying. If you got it right, it's quietly triumphant.
If you get stuck
Three sealed hints, in order.
Three sealed hint envelopes are included in every box, clearly labelled. Open them in order. Each one nudges you toward a line of inquiry rather than handing you the answer.
If you'd rather not break a seal, email us at hello@cosykiller.com with your case number and the document you're stuck on, and we'll write back.
Time commitment
Six to eleven hours.
Depending on the case. You'll see a solve-time estimate on every product page.
Most groups spread it across two or three sittings. Pour a drink, clear a table, and give it the evening it deserves.
Ready?
Pick a case.
Five unsolved murders on the shelf. One of them has your name on it.
Browse the cases