How to play Daily Atlas — Country Deduction

Daily Atlas is a deduction puzzle built out of geography rather than a geography quiz, and the difference between those two things is the entire design.

The problem with geography quizzes

A quiz asks what you already know. If you know it you answer in four seconds and if you do not you leave. There is no middle, no working out, and nothing to get better at except memorising more.

This gives you a target you almost certainly cannot name and then hands you enough information to find it anyway. Every guess answers with three things: the great-circle distance to the answer in kilometres, the compass direction you would travel to reach it, and how close that leaves you as a percentage of the furthest you could possibly be.

That is enough. A solver using nothing but those answers — no map, no knowledge, only the numbers the game prints — finds every country in the atlas inside the six guesses allowed, and usually inside four. Whether you can do it as fast is a matter of practice, but the information is there, and it is there for every single target.

Reading the answers

The distance is a true great-circle distance between country centres, so it is symmetrical and it does not care about borders or oceans.

The arrow is the initial bearing, rounded to one of eight directions. It is the direction you would set off in, not the direction the answer lies on a flat map — on long journeys near the poles those differ, which is a real thing about the world rather than a quirk of the game.

The percentage is one minus the distance over half the Earth's circumference. Ten percent means you are most of a world away. Ninety percent means you are close enough that only a handful of countries qualify.

The method

Open with anything central; the first answer eliminates most of the planet by itself. Then guess in the direction the arrow points, roughly as far as the distance says. The second answer usually cuts the possibilities to a region, because very few countries sit at both of those two distances at once.

By the third guess you are normally choosing between neighbours, and the arrow tells you which one. The common mistake is guessing somewhere you think is right rather than somewhere that splits the remaining possibilities — a guess that can only confirm what you already believe learns you nothing.

The compass

Above the board, each guess is drawn as a line from the centre at its true bearing, its length set by how far off it was. A near miss is a short line; a guess from the far side of the world is a long one. Five lines all pointing inward is what a solved puzzle looks like before you have solved it.

The day

One country a day, the same one for everybody. It is drawn from a shuffled order rather than picked at random, which matters more than it sounds: a random pick repeats inside a fortnight, and a player who is handed the same country twice in a month stops believing the puzzle was built rather than sampled. A shuffle cannot repeat until every country in the atlas has had its turn.

The day rolls over at your local midnight. Streaks count consecutive days solved.

The share

Finishing gives you a block of squares and arrows. The squares show how close each guess was and the arrows show which way it pointed. There are no country names and no distances in it, so it spoils nothing, and there are no words in it at all, so it reads the same in every language.