How to play Borderline, the daily borders game

The map in Borderline shows land, coastlines and the great lakes, and nothing else: no borders, no names, no cities. On top of it, at the centre of the screen, sits a single highlighted line. It is a real stretch of land border, and your job is to slide the map underneath it until the line lies exactly where it runs on the ground.

It sounds simple until you try it. Borders that you could draw from memory on a labelled map become strangely hard to place when the only clues are the shape of a coast and the curve of the line itself. That is the whole game: reading shapes, distances and orientation, and trusting your mental atlas.

A new day arrives at 01:00 Paris time, together with every other Letsdle game. If you began the previous day's lines just before the switch, you get a quarter of an hour of grace to finish your pose. Everyone plays the same four lines on the same day, and each day has an edition number, so « Borderline #12 » can be compared without giving anything away.

• Lines 1 to 3 each follow one country's land border with up to three of its neighbours in a row. A country with three neighbours or fewer may come with its whole land border.
• The three lines are spread across the world: two lines in a row are never on the same continent, and they lie more than 1,500 km apart.
• Each line is a little harder than the one before.
• Line 4 is the HARDCORE line: a chain of borders between several countries, somewhere else again, with one more thing for you to judge, its size.

A day is worth 100 points at most: 25 for each line. It is free, needs no account, and your progress is kept if you close the page and come back.

Each of the first three lines is played in three short steps.

• Pose. The line comes alone, at its real size and with its real orientation: you never rotate or resize it, you only choose where it goes. Drag the map (or use the arrow keys, + and − to zoom), then press Pose. If you haven't moved the map at all, the game asks you to confirm first.
• Name the country. Before the answer is shown, you may name the country whose border this is, the one the line partly goes around. A right name is worth 2 points; you can also skip.
• Find the neighbours. After the reveal, name the countries on the other side of the line, one at a time and in any order, for up to 3 more points. A wrong name costs nothing, but the step closes at the third wrong one.

The line tells you more than its shape. Its core changes style at each neighbour (a solid line, long dashes, a dash-dot pattern) and a round mark sits at every point where two sections meet. So before you even pose, you know how many neighbours the line runs along, just not which ones.

On every line, two hints are on offer, one after the other. The first tells you that line's continent, for 5 points on that line. The second lights up in orange on the map the region where most of the line runs, for 10 points more: 15 with both. A region is a part of a continent: the Americas and Oceania stay whole, Europe is split in two, Africa and Asia in five. The orange area is drawn in broad strokes, never along a border, and part of the line can run outside it. Both hints are optional and only worth it when you truly have no idea.

Once you pose, the game measures the distance in kilometres between your line and the real one, on the globe. That distance alone sets the pose points.

• 50 km or less: the full 20 points.
• Beyond that, points fall away gradually: about 16 at 100 km, 14 at 150 km, 10 at 300 km and 5 at 750 km.
• 2,000 km or more: nothing for the pose, though the name and the neighbours can still earn points.

Each pose also gets a band: Spot on up to 150 km, Close up to 750 km, Far beyond. The bands give the colours of your share text and of the line on the map once it is revealed.

The neighbours step is shared out fairly: 3 points times the share of neighbours you found, rounded down. Find all of them for 3, two out of three for 2, one out of two for 1. A line can never go below zero, even with the hint.

The last line of the day changes the rules. It is not the border of one country but a chain: two to five border sections in a row, running between several countries, or a single border at least 1,500 km long. There is no country X to name; both hints are on offer here too.

Above all, the chain comes without its size. You see its shape and its real orientation, but not how big it is. It starts at 1,000 km end to end, and you set the size yourself with the slider (from 100 to 10,000 km), the − and + buttons, or the [ and ] keys, which change it by 10 % a press. Move the map, adjust the size, then pose.

The pose is then scored on the mean distance between your chain and the real one, measured at points spread evenly along it, with the same 20-point curve as the first three lines. A chain of the right size placed at the right spot scores the most; a chain of the wrong size drifts away at its ends, so the size error is already counted in that average. The reveal tells you whether your size was right (within 20 %), too small or too big, but that verdict is only there to help you learn: it adds or removes nothing.

Then comes the last step: name the countries the chain separates, for up to 5 points, with the same rule of three wrong names. The game tells you how many countries there are to find.

When the four lines are done, an end card sums up the day with a road sign: Perfect for the full 100, Nice chain from 60 points, Not bad from 25, and Lost on the map below that. Each line shows its band and its points.

The share text contains only coloured squares, one per line: green for Spot on, yellow for Close, red for Far. A light bulb follows the square of each line for each hint you took there (two with the region), and a warning sign follows the fourth, the HARDCORE line. No country and no map ever appear in it.

The stats page keeps your days played, your current and best streak of finished days, your best and mean totals, your poses by band and your median error on each line. The archives let you replay past days: the last seven are free for everyone, older ones come with Letsdle Premium, and a replayed day counts apart from your streak.

Disputed areas follow a neutral rule: a disputed territory is taken out of every country that claims it, so the border you play is where the countries really touch. The map comes from Natural Earth at 1:10m, in the Web Mercator projection.

• Look for the sea. Many land borders end on a coast. If one end of the line looks like it should meet the water, slide that end onto a shoreline and see whether the rest of the line follows the land.
• Use the line's size as a clue. Lines 1 to 3 are drawn in the map's own projection, which stretches everything towards the poles. A line only fits the land around it near its true latitude, so if it looks far too large or small for a region, move north or south rather than sideways.
• Read the pattern before you pose. The number of styles in the line is the number of neighbours. A long line with four or five sections points to a country surrounded by land; a short one with a single style may be a small border or a country with only one land neighbour.
• Get the region first, then the detail. Zoom out to choose the continent and the coast, then zoom in to line up the curves. Being 400 km off still earns points; being on the wrong continent earns nothing.
• On the HARDCORE line, shape before size. Find where the chain's bends and its overall direction match the land first, at the starting size, then grow or shrink it until its ends fit. The slider is in real kilometres, so the line looks longer on screen when you move it far from the equator: that is the projection, not your setting.
• Try names freely. In the neighbours and countries steps, a wrong name costs nothing until the third, so offer the obvious candidates first and keep a guess or two for the end.
• Save the hint for the rare blank. Five points is a quarter of a good pose: unless the line could honestly be anywhere, a rough guess at the continent costs less.