How to Play Flagdoku: Rules and Tips for the Daily Flag Puzzle

Flagdoku is a daily geography puzzle in which you fill a 3×3 grid with 9 flags. Each cell sits at the intersection of a row criterion and a column criterion, and the flag you place there must satisfy both at once. You score 1 point per correct guess, wrong answers score nothing, and the maximum is 9. A new grid appears each day, and you can replay older ones through the archive.

The core mechanic

The grid works like a logic puzzle rather than a quiz. You are not asked "which flag is this?" — you are asked "which flag belongs in this position?"

• Every row carries a category (for example, a region, a color, or a design feature).
• Every column carries a different category.
• The flag you guess for a cell must match the row category and the column category simultaneously.

Because the categories overlap, the puzzle rewards elimination as much as recall. A flag that fits the row but not the column is still wrong.

Scoring and feedback

Wrong answers do not deduct points, so there is no penalty for testing a flag you are unsure about — but they also give you nothing, so it pays to reason before guessing.

The flag of the day

One flag in the set is the flag of the day: it fits every category in the grid. Finding it is effectively the puzzle's centerpiece, and it can help you anchor the rest of the board once you identify it.

Daily format and the archive

A new Flagdoku is available each day. To play previous puzzles, open the Archive, or click a #Number cell to jump to that day's grid. The site also provides Search and Help options in its navigation.

How to approach a grid

1. Read all row and column criteria first. Do not start guessing before you know every constraint — the categories interact.
2. Find the most restrictive cell. The intersection of two narrow categories (for example, a specific region plus a specific design element) usually has the fewest possible answers.
3. Work from certainties outward. Once a flag is confirmed, it rules out candidates in its row and column.
4. Use the flag of the day as an anchor. If you can identify it, it resolves one cell and constrains the rest.
5. Guess only when reasoning stalls. Since wrong answers cost nothing but earn nothing, a guess is a fallback, not a strategy.

Common sticking points

• Matching only one criterion. The most frequent mistake is choosing a flag that fits the row but ignores the column, or vice versa.
• Assuming a flag is unique to a category. Many flags share colors and symbols, so a category may have several valid candidates — the grid narrows them, not your memory alone.
• Forgetting the daily reset. Each day brings a new grid; yesterday's logic does not carry over, though the archive lets you return to it.

Flagdoku suits players who already know a range of country flags and enjoy constraint-based puzzles. If you are still building flag knowledge, the archive is a low-pressure way to practice the format before chasing a perfect 9.