Daily Hidden Rule is a daily geography deduction puzzle. Some countries of the world follow a secret rule, and all other countries do not.
You test countries on the world map to learn which countries fit. Then you pick the rule from a list of 16 possible rules.
Every player in the world gets the same rule and the same list on the same day.
The rules come from geography, languages, politics, history, money, flags, country names, sport and culture.
How to play
Tap a country on the map to test it. A country that fits the rule turns blue. A country that does not fit turns grey.
With a mouse, a click tests the country. On a touch screen, tap a country to select it, then tap Test.
A tested country shows a number. The number tells you how many of its land neighbours fit the rule.
Use your tests to find which rules in the list cannot be true. Cross out a rule to keep track. Crossing out is free.
When you know the rule, select it in the list and tap Guess. You have 3 guesses.
Drag the map to move it. Use the wheel, a pinch or the + and − buttons to zoom.
A new rule starts every day at 17:00 CET (Europe/Oslo time). Find the rule on consecutive days to grow your streak. The Share button copies your result with no spoilers.
What counts in this quiz
You start with 100 points. Your first 3 tests are free.
Each test after the free tests costs 10 points. Each wrong guess costs 10 points.
When you find the rule, you keep at least 10 points. You can test up to 40 countries in one day.
If you use all 3 guesses, or if you show the rule, you get 0 points and your streak ends.
Your rank today compares your points with the points of every other player today, guests included. If two players have the same points, the player with the shorter time ranks higher.
A run with 0 points gets no rank, and the rank does not count runs with 0 points.
The leaderboard ranks signed-in players by their streak of solved days.
What's not included, and why
The board has the 197 countries of the world countries quiz. Territories such as Greenland, Puerto Rico and French Guiana are on the map, but you cannot test them.
Borders are land borders of the main country only. Overseas land does not count, so France does not border Brazil in this game.
Rules about names use the English names that the map shows when you point at a country. For example, the map says Czech Republic and Ivory Coast.
Rules about population, area, flag colours, the main religion and the currency use the same data as Daily Country.
A star on the flag counts when it is in a coat of arms too.
Each rule in the list differs from the hidden rule in 4 countries or more. So a test can always tell the hidden rule apart from each other rule in the list.
Good to know
The rule bank holds more than 100 rules. Every rule in the bank can be the hidden rule.
A hidden rule does not come back for 40 days.
4 rules in each day's list are close to the hidden rule. For example, the EU and the euro share most of their countries.
A test of a large country with many neighbours, such as Russia or China, tells you a lot about the countries around it.
The free tests are the best time to test countries that split the list in half.