ECHO EXPEDITION
A survey in miniature

Take a different point of view

Bring the cave
into focus.

Six landmarks. Eighteen battery. The map is entirely visible, but a good survey needs two useful bearings. Walk, listen, and bring your notebook home.

Battery remaining
Current square
Landmarks fixed
Score

The survey map

Practice expedition

Move one square at a time. The tinted area is today’s pulse range: Manhattan distance 1–4. Crystals transmit echoes through rubble; rubble blocks walking only.

◎ you⌂ camp◆ landmark▧ rubble

The map is open and the battery is full. Read the pulse preview before setting out.

Six echoes to bring home

All values visible

A first echo logs a landmark. Another echo must come from a point off the same straight line through that landmark. Opposite bearings on one line still do not fix it.

How two bearings become a fix
  • Your first observation and the landmark define a line. The second observation must be off that line, within range, and not on the landmark itself.
  • From a landmark at C3, observations at A3 and E3 are opposite but still collinear: no fix. A3 and C1 make a useful angle.
  • Equivalently, for vectors from the landmark to the two observation squares, dx₁ × dy₂ − dy₁ × dx₂ must not equal zero.
  • Only the first origin and the successful second origin are retained. Any useful second bearing completes the fix; no extra points for later pulses.

The surveyor’s commands

No rush, no hidden terrain

move N · pulse · finish
preview move E, preview pulse, and preview finish are free. So are state, moves, map, and help.

Complete public text state
Every legal command right now


A short expedition, an exact score
  • You start at camp C3 with 18 battery. Walking one orthogonal square costs 1; a pulse costs 2. You cannot enter rubble or leave the map.
  • A pulse reaches every landmark at Manhattan distance 1–4: |column difference| + |row difference|. There is no line-of-sight blocking. Standing on a landmark is too close to read it.
  • A landmark’s first echo earns its printed value. A valid second bearing adds twice its value, for three times the value when fixed.
  • Ending at camp with at least three fixes earns 20 points plus remaining battery. Away from camp, or with fewer fixes, there is no return bonus. Returning is optional; all survey points still count.
  • Finish expedition ends immediately with the score shown by preview finish. The game also ends automatically when battery reaches zero. Fixing all landmarks leaves you free to return home.
  • The live score includes survey points; the camp bonus is added only when the expedition ends. Higher is better. All three map editions use the same rules and landmark values.
Planning and visit storage
  • The pulse preview names every new log, useful fix, collinear repeat, out-of-range landmark, and too-close reading. Nothing is hidden.
  • The camp path length follows walkable squares; pulse range ignores rubble. These are intentionally different measurements.
  • The three map editions change obstacles and landmark locations. The current map is fully revealed before the first move.
  • Invalid commands do nothing. Batches stop at the first invalid action or failed check; earlier successful actions remain applied.
  • Browser storage is optional. Keep this page open; a sandboxed reload may lose your survey.



Field notebook
0 actions