A strategy guide to The Cartographer’s Lie

The rules fit on a postcard: one hex on today’s chart is drawn as something it is not, every survey note you are given is true, and only one hex can satisfy all the notes at once. Finding it is a different matter. This guide is about the finding: which note to take first, what each kind of note actually eliminates, where the clock is really spent, and the mistakes that cost most people their corrections. If you have not played yet, start with how to play, which has a short interactive tutorial. Terms in italics are explained in the glossary.

The one idea that matters

You are not guessing. Each note is a filter, and a filter is only useful if you apply it to every hex on the island, not just the ones that look promising. Players who lose their three corrections almost always did the same thing: they read a note, found a hex that fitted it, and filed. The note was true of that hex, and of a dozen others. The game is won by elimination, and elimination means asking of every hex, “could this be the lie?”, and striking it out the moment a note says no.

The notes describe the chart as it is printed, including the lie’s own hex. “The lie is drawn on reef or sink” means the symbol printed on the lie is one of those two. “The lie touches exactly one heath” counts the heath hexes printed around it. You never need to know what the lie should have been; you only need to find where the printed chart and the true notes disagree about a single hex.

Before the clock starts

The chart is face down until you turn it over, and the clock starts then. The one thing you can read for free is the key under the board, which names every ground, landmark and reading on today’s island. Read it. A note that says “every trig point” is only useful if you can tell a trig point from a beacon at a glance, and the thirty seconds you spend on the key before the clock runs are thirty seconds you do not spend during it.

The order to take the notes

Notes are not equal. Some remove three quarters of the island in one reading; some remove three hexes. Take the big cuts first and the small ones last, so that by the time you reach the fiddly note there are only a handful of hexes left to test it against. In rough order of how much they usually eliminate:

1. Sheet notes. “The lie falls on Sheet II.” The dashed lines are district boundaries, and the sheets are numbered on the chart. Everything outside the named sheet is gone. This is the best first note on any chart that has one.
2. Drawn-on notes. “The lie is drawn on reef or sink.” Strike every hex printed as anything else. Two grounds out of six usually leaves a third of the island.
3. Neighbour counts. “The lie touches exactly one heath.” Every hex has up to six neighbours; the ones on the coast have fewer. A count of zero is quick to apply, since any hex next to a heath is out. A count of two or three takes real counting, so leave it until the field is small.
4. Bearings. “The lie lies north-east of every beacon.” See the next section, because this is the note people misread most.
5. Within-distance notes. “The lie lies within two of a surveyed wreck.” Distance is counted in hex steps. Draw the ring in your head from each qualifying landmark, and strike everything outside every ring.
6. Shortest-path notes. “The lie lies on a shortest path from a beacon to a trig point.” On a hex grid two points can have several equally short routes, and together they make a lens between the two landmarks. The lie is somewhere in the lens. This note is most useful once the field is already narrow.
7. Isolation. “Nothing adjacent to the lie shares its ground.” The lie is an island of one: every neighbour is printed as a different ground. Check the survivors against it last.

Bearings are strict

A bearing note quantifies over every landmark it names, and it means the compass direction exactly. “North of every beacon” means the lie is north of each beacon on the chart, so the one that matters is the northernmost beacon: anything level with it or south of it is out. “North-east of every beacon” means north of each one and east of each one, both at once. It does not mean “roughly up and to the right”. A hex that is north of a beacon but level with it east-to-west fails the note.

This is why two bearings that sound like they contradict each other are a gift. “North-east of every beacon” and “south-west of every wreck” corner the lie in a wedge between the two sets of landmarks, and the wedge is often three or four hexes. The compass rose in the corner of the chart shows which way is north; the hex grid’s rows run east to west.

Marks, and the strip of notes

Click a hex once to mark it as a maybe, twice for probably, and hold it to strike it out. The marks are yours and the chart never reads them, so use them freely: the fastest solvers strike as they read, note by note, and never hold more than one note in their head. The strip above the board carries the notes one at a time. Tick a note off when you have applied it in full; the tick is what the share grid is drawn from afterwards.

On the Standard chart you can ask the board to show what a note rules out, and it costs a minute of judged time each time you use it on a new note. It is worth it on a neighbour count you would otherwise miscount, and a waste on a sheet note you could apply in five seconds.

When to file a correction

You have three corrections, and a refused one costs three minutes on top of the time it took you to make it. Three minutes is longer than most people spend finding the answer properly, so the arithmetic is simple: filing on a hunch is almost never faster than finishing the elimination. File when exactly one hex survives every note. If two survive, you have misapplied a note; go back to the bearings first, because that is where the error usually is.

If you do have to choose between two, choose the one that satisfies the note you are least sure you applied correctly. A refusal still tells you something: the X is stamped on the chart in the cartographer’s ink, and the other hex is now the answer.

The harder charts

The Casual and Standard charts use the note forms above. The Hard chart, in the apps, adds denials: “The lie is not within three of any trig point”, “The lie is not drawn on heath”. A denial is still true, and the way to apply it is to ask where the plain claim would hold, find every such hex, and strike them all out; the lie is elsewhere. People lose time trying to picture the complement directly. Find the positive set, then remove it.

The Fiendish chart adds a second axis: depth. Hexes carry printed soundings in fathoms, one of them is a misprint, and a second set of notes describes the true depth (“shallower than the number printed on it”, “matches a number printed on a hex beside it”). The two puzzles interlock: the lie on the chart and the misprinted sounding are the same hex, so each set of notes narrows the other. Solve whichever axis has the bigger first cut, then carry the survivors across.

Where the time goes

The time on your record is the judged time: the clock, plus three minutes for each refused correction, plus one minute for each note shown on the Standard chart. It is the number the daily board ranks on and the one a share link carries as a time to beat. Most Casual charts take two to four minutes solved cleanly. A chart solved in six minutes with no refusals beats one solved in four minutes with one, so the clock is less of an enemy than it looks.

Streaks, and keeping them

Finishing a chart on a day, solved or not, counts the day. A solved day extends your streak; a lost day does not break it if you have a freeze left, and one freeze is granted every calendar month. A freeze also covers a day you miss altogether, one per month. Members of the Cartographer’s Guild in the apps have freezes without limit, so a bad day or a day away never costs the run. The streak is kept for the browser you play in; signing in with Apple or Google carries it across devices and into the apps.

Sharing a result without spoiling it

The share grid shows one tile per note in the order you struck them off, with the slowest note in a different colour. It never shows what a note said or where the lie was, so it is safe to post before a friend has played. The link under it opens today’s chart and carries your time as a challenge. A new chart is drawn every day at 5am New York time, the same island for everyone.