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Start with An Inheritance of Murder. It's our gentlest case, built for puzzle-minded beginners — Braille, letter-to-symbol substitutions and one-time cipher pads. The Secret of Site Q is the step up: a longer, cross-referencing investigation that's challenging but solvable. Shadows in the Gallery is our most advanced case, layering Playfair, knock code and Caesar ciphers across a post-war art theft — do it once you've worked one of the others.

Cosykiller is written mainly for adults, but families can participate together. Every case is rated 14+ for themes of murder, and Shadows in the Gallery touches on wartime violence and post-war trauma, so we'd steer younger players towards An Inheritance of Murder first.

It varies by case, but every box contains a cover letter from Fairhall & Brett Inheritance Recovery — the fictional investigators who brief you on the case — followed by the documents like photographs, ciphers, maps, letters, military archives, telegrams, postcards, and other personal effects collected during the investigation. Some cases include dried botanicals, spices, theatre programmes and small physical objects. Each case is a complete story, with the final solution provided at the end. Nothing to download or sign into.

2-4 hours for our single box solves, and between 6-11 hours for some of our longer games. Length of time also depends on the number of players, and how much you like to re-read and how quick you are at spotting and solving ciphers. Most people spread a case over two or three evenings. You can pause whenever you like — put the lid back on, come back next weekend. Nothing expires.

Both work well. Every case is designed to be solvable on your own — no mechanic depends on a second reader. That said, two to four players is where a case shines, because half the fun is arguing civilly about motive over a drink.

If you become totally stuck on a code, check out the <a href="https://fairhallandbrett.co.uk/" target="_blank" rel="noopener noreferrer">inheritance hunter's website</a> or join the online community where other detectives swap ideas (link included with your order). If you need one on one help then email <a href="mailto:supersleuth@cosykiller.com">supersleuth@cosykiller.com</a> with your case number and the document you're stuck on and we'll help without spoiling things for you.