How to play
Reading the chart
Every ground is engraved linework on tinted paper, the way a printed hydrographic chart draws shallows, rubble and marsh — never a flat colour block. Each hex also carries its two-letter code. Landmarks are drawn solid when the survey confirmed them and dashed when only reported. The chart key under the board names every symbol on today’s island, and a note names its landmark exactly, so the key is worth opening before you start. The first lesson below is the key itself.
Dashed lines are district boundaries — the sheets a note means when it says Sheet II. The solid outer edge is coastline.
One hex on this chart is a lie.
A cartographer drew it, and hid one false entry in it — a single hex drawn as something it is not. Every survey note you are given is true. Only one hex can satisfy all of them at once. Find it and file your correction. You get three.
Read the key first
Every note names something on the chart, so the key is the first thing to open on any island. Six grounds, each with its tint, its engraved symbol and a two-letter code on every hex. Landmarks — beacons, trig points, wrecks — drawn solid when the survey confirmed them and dashed when only reported. Readings: a magnetic anomaly, a tidal race. The dashed line is a sheet boundary; the solid edge is coast. This small chart carries one of each, and the key below lists exactly what is on it.
Ground
- He · heath
- Sc · scree
- Re · reef
- Si · sink
- Sh · shoal
- Sa · saltmarsh
Landmarks
- a surveyed beacon
- a reported wreck
- a surveyed trig point
Readings
- magnetic anomaly
- tidal race
Boundaries
- District boundary
Your marks
- maybe one click
- probably this one two clicks
- ruled out press and hold
The daily has the same key, listing only what is on that day’s island. Open it before you read the first note.
Filing a correction
Select a hex and file. You get three corrections. A refused correction is stamped on the chart with an X in the cartographer’s ink — distinct from your own single strike, so you can never mistake the chart’s verdict for your own reasoning — and adds three minutes to your time. Spend all three and the day is over. Signed in, the chart then shows where the lie was; as a guest it does not, so that an answer cannot be carried into a fresh tab. The time on your record is the judged time, the clock plus every penalty, and it is what the daily board ranks on.
The chart here, and the chart in the app
A new chart is drawn daily at 5am New York time, and it is the same island in the browser and in the app — the two run the identical engine. The web serves the Casual and Standard tiers. Hard, streaks, ratings, the career ladder and daily duels live in the app, and the Fiendish chart is part of the Cartographer’s Guild membership.
Sign in and a chart you finish here counts: it adds to your solve total and keeps your streak alive, and both are the same numbers the app reads — finish the same chart on both and it counts once. Ratings, career points and duels stay in the app. Signed out, nothing is recorded at all.
Frequently asked questions
What is The Cartographer’s Lie?
A daily deduction puzzle on a hand-drawn nautical chart. One hex of the map has been drawn as something it is not — the lie. Every survey note you are given is true, and only one hex can satisfy all of them at once. You find that hex and file a correction.
How do I play?
Read the survey notes and eliminate hexes. Each note — a compass bearing, a count of neighbours, a sheet location, a ground type — is true of the lie, so together they narrow the island to a single hex. Select that hex and file your correction. You get three corrections. If all three are refused the day is over, and a signed-in player is shown where the lie was.
What does a compass bearing note mean exactly?
Bearings are strict. “The lie lies north-east of every beacon” means the hex is north of every beacon AND east of every beacon, both at once — not roughly in that direction. Two bearings that sound contradictory corner the lie between them.
What does a note like “the lie is not within 3 hexes of any trig point” mean?
On Hard charts, some notes are denials (“is not”, “does not touch”). The note is still true: it tells you what the lie is not. Ask where the plain claim would hold, find every such hex, and rule them all out — the lie is elsewhere.
What is the time penalty?
The clock starts when you begin the survey and never pauses. A refused correction adds three minutes. On the Standard chart, showing what a note rules out on the map adds one minute, charged once per note. Your judged time — the clock plus every penalty — is the time on your record, on the daily board and in duels.
What are the four tiers?
Every day draws four charts of the same island. Casual has three or four gentle notes, and showing a note on the map is free. Standard uses the full note vocabulary, and showing a note costs a minute. Hard adds denials, holds the decisive note to the end, and shows nothing for you. Fiendish prints a depth on every hex, and one of the numbers is the lie. Casual and Standard are on the web; Hard and Fiendish are in the app.
What are soundings on a Fiendish chart?
Every hex prints a depth in fathoms. Exactly one printed number is a misprint, and that hex is the lie. The notes describe its true depth — what the sea actually measures — which is never the printed number. You name both the hex and its true depth.
Is it free, and when does a new puzzle appear?
It is free to play in the browser. A new chart is drawn every day at 5am New York time, the same chart for every player. The Casual and Standard tiers are on the web; Hard, streaks, ratings and duels are in the free app, and the Fiendish chart is part of the Cartographer’s Guild membership.