It takes about three minutes and there is nothing to install, sign up for, or pay.
Every day there is a single mystery, and it is the same one for everybody in the world. It changes at midnight where you are.
You start with one clue. It will be the vaguest of the five, and it is meant to be. Type a guess whenever you think you have it. Get it wrong and the next clue appears — but the hand on the clock moves forward an hour.
Solve it at one o'clock and you take five points. At two o'clock, four. All the way down to one point at five o'clock. Miss it entirely and you take none, but nothing else is lost.
Skip pulls the next clue without a guess, and costs an hour just the same. The free clue is different: it is offered in exchange for watching a short video ad, it reveals a clue without moving the hand, and it is entirely optional. Ignoring it costs you nothing at all.
Solving the daily mystery keeps your streak alive. Miss a day and the streak resets — but your points never do, and they carry you up through the ranks from Nightwatch to Grand Horologist.
Every mystery ever published stays free to play in the vault. Vault mysteries give points but do not touch your streak, so the streak keeps meaning what it says.
On your device, in your browser. There is no account and no server, which means nothing to sign up for and nothing of yours to leak — and also that your progress does not follow you from your phone to your laptop.