Map a county by sight, by angle and by error.

THEODOLITE is a free survey incremental that plays in your browser. The county exists only as a hearsay sketch in pencil: hills said to be there, woods that may be bigger than drawn, towns with question marks after their names. Two trig stations stand at the ends of a measured baseline. Everything else you have to fix for yourself.

The one rule

A station is fixed once its sights to two fixed stations are read. It inherits the worse error of the pair, plus a little for every cell of sight, times the shape of the triangle: a right angle at the new station fixes it well, a thin sliver fixes it badly. Chain station after station away from the baseline and the error piles up. Where you put the next station decides how well the county is known.

Three things that pull against each other

  • The network. Two stations share a sightline only if the line between them clears the hills and the woods. Hover the map to see what a station would see: green where it sees, orange where the ground is in the way, and the error it would be fixed at before you spend a coin. Towers lift the eye, and hovering a station with TOWER shows which sights a lift would open.
  • The field work. Observing parties read the sightlines one at a time. Plane-table parties ink the ground round every fixed station, hachures, woods, hedgerows, lakes and contour lines, and later redraw any cell a better station could draw more truly.
  • The weather. Every day is clear, hazy or foggy, with more fog in autumn and winter. Haze stops the long sights; fog stops them all.

Sheets, grades and reissues

Each of the eight towns buys the sheet of land round it once 90% of it is mapped, graded A, B or C by its mean error. Sell a sheet at C now and pay for the next station, or wait for the grade. When the survey improves you can reissue it. The county is done when every sheet is in print at B or better.

Ten instruments

More observing and plane-table parties, a longer telescope, a better alidade, a finer vernier, heliotropes that flash through the haze, a mule train, a check baseline that wipes the error off both its ends, a barometer and a printing press. The Board grants them as your sheets come out.

Nothing restarts

It saves as you go. While you are away your parties keep working, up to one season, weather and all. Every new county is a different map.

Controls: tap or click. 1 raise, 2 tower, 3 read, the arrow keys and Enter act from the keyboard, B publishes the next sheet, T changes tabs, F toggles 3x speed, P pauses, H opens the help, M turns the sound off. Plays on desktop and phones; on an upright phone it switches to its own tall layout, and a first tap shows a station's sightlines before a second raises it. About fifteen to twenty minutes to a finished county at normal speed.

Paid, from the same studio

  • DOWSER ($9.99): minesweeper with no numbers, sweeping a dowsing rod across an old field and reading the tone your own hand draws out.
  • STRINGLINE ($9.99): a castle hall whodunit where every clue is a line you draw.
  • MILLWRIGHT ($5.99): raise three windmills in a farming parish, where every farm carts its sacks to the nearest mill.

Credits and disclosure. Made by Core Systems Asset Factory. Code and text were written with AI assistance. Every picture in the game is drawn by code written for it: every hill, wood, town and trig station, plus two plates from our procedural pixel engine. The cover is composed from the game's own renderer. The music and the sound effects are synthesised by code, with no generative audio model.

More free browser games: STAGHORN, GASHOLDER, CLERESTORY. Everything we make: csaf.itch.io.

More information

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