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Mysteries & Riddles
Logic mysteries, cipher tools, unsolved cases and ARG-shaped sites that never quite explain themselves. Deduction as entertainment.
17 sites
Code-breaking tools and a cipher identifier for when you have a string of nonsense and no idea what it is.
- <1 min
Tens of thousands of riddles, brain teasers and lateral thinking problems submitted by users since 1999.
Chain encoders and classical ciphers together and watch text transform between formats at each step.
- <1 min
- Desktop
GCHQ's public knife for decoding and decrypting data, built by dragging operations into a pipeline.
- 10 min
- Desktop
Several hundred cipher, code and puzzle solvers in one place, from Caesar shifts to crossword pattern matching.
- <1 min
Decades of archived puzzle hunts from the hardest annual competition of its kind, all of it still playable.
- 1 hr+
- Desktop
A daily logic murder mystery with suspects, weapons and locations, solved by grid deduction in about ten minutes.
- 10 min
The American government's public database of missing and unidentified persons, searchable by absolutely anyone.
- 10 min
The riddle that calls itself the hardest on the internet, played by editing URLs and reading page source.
- 1 hr+
- Sound on
- Desktop
Free monthly puzzle sets designed to be solved in a pub, with a decade of archives you can print at home.
- 10 min
A question site where people post original puzzles and strangers solve them properly, with the reasoning shown.
- 10 min
Millions of pages of declassified government documents prised out by freedom of information requests, free to browse.
Profiles of thousands of American cold case disappearances, written and maintained by one person for decades.
A volunteer register of unidentified remains and missing people, matched by amateurs who keep on succeeding.
A crime you solve by writing database queries, and easily the least painful SQL tutorial ever built.
- 10 min
- Desktop
The community record of Cicada 3301, the recruitment puzzle whose final book has still never been deciphered.
The long-running forum where amateur investigators pick apart cold cases, for better and occasionally much worse.
How we picked these
Every entry in Detour is hand-sorted rather than scraped: filed under one category, given one to three moods, and placed in a time band for how quickly it pays off. The practical facts — cost, sign-up, sound, device and whether it is safe at a desk — are recorded per site and shown on every card, so you can rule things out before you click.
Mysteries & Riddles: questions
How many sites are in Mysteries & Riddles?
17 sites, each hand-sorted by category, mood and how long it takes to pay off.
Which of these sites are free with no sign-up?
17 of the 17 are free and need no account. None of them are paid.
Do these sites work on a phone, and are they safe for work?
12 of 17 work on a phone; the rest are desktop only. 17 are safe for work and 16 work with the sound off.