GeoDuo

GeoDuo

About GeoDuo and its maps

GeoDuo is a free geography game: discover one border and two countries every day.

Play the daily challenge

One shared challenge every day

The challenge changes at 00:00 UTC. Everyone plays the same border, regardless of language. The catalog contains 342 country or territory pairs and cycles through them before repeating. The archive lets you play earlier days starting on September 19, 2026.

Progress stored in your browser

No account is needed. Games, streaks and preferences are stored locally in this browser. They do not sync between devices and may be lost if you clear site data. Sharing copies your guesses and a link without revealing the countries.

Where the borders come from

Geometry comes from Natural Earth's public-domain 1:10m mapping. GeoDuo uses shared boundaries between countries and territories, excluding maritime borders. Lengths are estimates and the terrain background is decorative. The catalog reflects this source and is not an official inventory of all current borders.

Includes all shared borders represented in the Natural Earth map data, including territories and disputed areas. Maritime borders are excluded. The boundaries reflect that source: examples of missing borders include Canada–Greenland and the short Botswana–Zambia section. This is not an official inventory of all current borders.

Explore Natural Earth mapping

HOW TO PLAY

One line. Two countries.

Identify the two countries or territories that share the displayed border.

  1. Select two countries and press Check. The order does not matter.
  2. You have six attempts. Correct names appear in green and can be kept in the next answer.
  3. Each incorrect answer unlocks a clue: regions, length, one country’s outline, the other’s outline, and finally both initials.
Neither country correct
One country correct: keep that name
Both countries correct: challenge completed
Map controls

Use two fingers to zoom and rotate the map at the same time. When zoomed in, drag one finger to pan. The compass restores north and the percentage resets the zoom. Zoom ranges from 75% to 250%.

At the initial size, drag the border to rotate it through 360°. Above 100% zoom, drag to explore; hold Shift to keep rotating. The compass points north: press it to smoothly restore the initial orientation. You can also use the arrow keys and Home. Zoom with +/−, the mouse wheel or a two-finger pinch. Zoom ranges from 75% to 250%; press the percentage to reset to 100% and center the map.

The border fits the view, without a kilometer scale that would reveal the length hint. The background terrain is decorative; some borders have several sections.

Each game is saved only in this browser. Use the history to play earlier challenges or continue unfinished ones. Challenges change at 00:00 UTC. Everyone follows the same schedule, without repeats until all 342 borders have been played.

About the borders

Includes all shared borders represented in the Natural Earth map data, including territories and disputed areas. Maritime borders are excluded. The boundaries reflect that source: examples of missing borders include Canada–Greenland and the short Botswana–Zambia section. This is not an official inventory of all current borders.

Overseas regions are grouped according to the source. A pair of countries may share several border sections, which are shown together.

Let’s play