Terrain and Production

Every square on the map has a terrain type. It may also have a river, a road, plowed fields or a special resource. Together these decide what a colonist working the square produces, how fast units cross it, and how well a unit standing on it defends. The Colonopedia shows a simplified summary. This guide gives the formula the game actually uses, and the numbers that come out of it.

The terrain figures come from the game's own data tables (UNFORESTED, FORESTED, OTHER and RESOURCE in COLTEXT0.DLL). The rules that turn those figures into production were read out of the reconstructed game code. Sources are listed at the end.

In the tables below, "free / expert" means what a free colonist makes, then what the matching expert makes (Expert Farmer for food, Expert Fur Trapper for furs, and so on). A dash means the square makes none of that good.

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At a glance #

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1. The terrain types #

There are eight open terrains and eight forests. Each forest sits on one of the open terrains, and clearing it turns the square into that terrain. Hills and mountains are never forested.

• Move cost is in whole moves. A colonist has one move (see §8).
• Turns count the turn you give the order. The number in brackets is for a Hardy Pioneer, who halves the time (rounding down). Plowing and clearing take 2 turns longer than a road on the same square.
• The Plow order is greyed out on hills and mountains. On a forest square the same order is called "Clear Forest".
• Colonies cannot be built on mountains, on water, in the top or bottom map rows (the Arctic Circle), or next to another colony.

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2. What each square produces #

This is the base production of every terrain, with no plowing, road, river or resource. The free colonist is the first number and the expert the second.

Ocean and Sea Lane squares produce only fish, which counts as food. See §5.

How these numbers come about:

• Food gets +1 on top of the data table on every square that grows any. This +1 is part of the formula, not a bonus you can earn.
• Lumber is the table figure doubled. So Mixed and Conifer forests give 6.
• Expert farmers and expert fishermen add 2. All other experts double their output.
• On the land, an Indentured Servant or Petty Criminal produces exactly what a free colonist does. The formula only asks whether the worker is the matching expert or a native convert (§10).

Tip: A free colonist on plains makes as much food as an expert farmer on prairie or grassland. Put your first farmer on plains, or on savannah if there is no plains.

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3. Plowing, roads and rivers #

Each improvement adds a fixed step after the base and the expert bonus:

• The step is 1 for free colonists, expert farmers and expert fishermen.
• The step is 2 for every other expert, and for anyone cutting lumber.

Furs get the road and the river twice. Before the steps, the fur yield already gets +1 for a road, +1 for a river and +1 more for a major river. A free trapper therefore makes +2 from a road and +2 from a river, and an expert, who doubles that earlier part, makes +4 from each.

The major-river rule is a trap. Food always takes its built-in +1 first, so a major river never gives more food than a minor one. A plowed field or a road also cancels the major river's extra. A major river is only worth more on unplowed crop land, or on a forest, hill or mountain without a road.

Food #

Cash crops (sugar, tobacco, cotton) #

On unplowed land a major river gives the same as plowed land with a river, for example 5 sugar on savannah, or 10 for an expert.

Furs, lumber and ore #

Tip: A road matters little to an expert lumberjack (+2 on 12), but it lifts an expert fur trapper from 6 to 10.

Worked examples #

• A free colonist on plowed plains with a river makes 7 food. An expert farmer makes 9. With Wheat on the square they make 9 and 13.
• An expert tobacco planter on plowed grassland with Prime Tobacco and a river makes 16. That is 3 doubled for the expert, doubled again by the resource, then +2 for plowing and +2 for the river.
• An expert fur trapper on mixed forest with Beaver, a road and a river makes 20. With Henry Hudson that becomes 40.

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4. Special resources #

• The "prime" doubling is applied before plowing and the river. Those still add only their normal step.
• A Minerals square appears to yield a little silver even though the terrain has none. The formula gives 1, or 2 for an expert silver miner, plus the usual road and river steps.
• Silver with no resource is barely worth mining. On a mountain without a Silver Deposit, a free colonist makes nothing unless the square has a road. With a road, or as an expert, the output is fixed at 1: no road, river or expert bonus applies.

Where resources appear #

Resources are not stored on the map. The game recalculates them from each square's position, a number picked when the map was made, and whether the square is forested.

• Within every 4×4 block of squares there are two candidate positions, two squares apart diagonally. Which two depends on that number, and on whether the square is forest or open land.
• Clearing a forest removes its forest resource. Because open land uses different positions, a freshly cleared square can occasionally turn out to hold an open-land resource such as Wheat.
• A native village square never shows a resource.
• Fisheries only exist near land. When the map is made, any ocean resource with no land within two squares (a 5×5 area without its corners) is erased.

Mines running out #

Each turn, a colony rolls once for each colonist mining ore on Minerals or mining silver on a Silver Deposit, and twice for each colonist mining silver on Minerals. A roll comes up with a chance that rises with difficulty: 1/2 · 2/3 · 3/4 · 4/5 · 5/6. Each success adds 1 to a counter that the colony's mines share. When it reaches 50:

• every Minerals or Silver Deposit square in that colony being worked by an ore or silver miner is exhausted at once;
• the "Mine depleted" message is shown;
• the counter drops back by 50.

For the average number of turns this takes on each level, see How Difficulty Affects the Game.

What is left afterwards:

• Minerals simply disappear, leaving ordinary terrain.
• A Silver Deposit becomes a "Depleted Mine". It still mines like a plain mountain, but without the plain mountain's limit: 1 silver for a free colonist and 2 for an expert, plus road and river steps. So a depleted mine with a road (2 / 4) still beats an untouched plain mountain (0 or 1 / 1).
• Ore Deposits on hills are never counted and never run out.

Tip: Put your ore miners on hills with an Ore Deposit. An expert there makes 12 ore, 14 with a road, forever.

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5. Water: fishing, coasts, lakes and the sea lane #

Ocean and Sea Lane squares both have a base fish yield of 3. That figure is then adjusted for how many of the square's 8 neighbours are also water. Land squares and off-map squares count as not water.

• Nothing is caught without Docks. The colony can only build Docks if at least one of its 8 surrounding squares is water.
• Lakes count. An inland lake is just enclosed ocean, so it is usually a 4-food square. Ships cannot enter a lake, though, and when you found a colony with water access only to a lake, the advisor warns that it has no port.
• Sea Lanes fish like ocean, but they are open sea far from shore, so in practice you will never work one.
• Fish is added to the colony's food.

Tip: The best fishing square is not open sea. It is a bay surrounded by land on three sides or more.

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6. The colony square #

The square a colony stands on produces food and one other good every turn without anyone working it. This does not use the terrain's normal food yield. The game uses a fixed figure instead:

On top of that:

• +2 food if the square has an Oasis, Wheat or Game.
• Extra food on the two easiest levels: see difficulty.md.
• +1 food at 50% Sons of Liberty and +1 more at 100%.

The secondary good is whichever of sugar, tobacco, cotton, furs, ore or silver the terrain yields most of. The game uses the raw data figure plus any resource bonus, and doubles it for a "prime" resource. Lumber is never chosen. On a tie the first in that list wins. It then gets +1 for a minor river or +2 for a major one, the Sons of Liberty bonus, and +1 on Discoverer. Plowing does not raise it.

Nobody works the colony square, so there are no expert bonuses, Tory penalties or Henry Hudson doubling.

Tip: Don't build your colony on the best farming square. On plains the colony square makes 3 food, but a farmer working that plains square would make 5 to 7. Build on prairie, grassland or tundra next to the plains instead.

Tip: Have a pioneer clear and plow the colony square. A forested colony square makes 2 food, a cleared one 3, and a plowed one 4.

Tip: A colony on hills makes 4 ore for free, which keeps a blacksmith busy from day one.

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7. Pioneers: clearing, plowing and roads #

The turn counts are in the table in §1. A job uses up 20 tools when it finishes. A pioneer left with fewer than 20 tools becomes a plain colonist again.

Lumber from clearing a forest #

When a forest is cleared, lumber goes to your nearest colony, if it is within distance 3. The game measures distance as the longer side plus half the shorter side, rounded down. So 3 squares in a straight line counts, and so does 2 squares diagonally. The colony doesn't need to be on the same landmass.

The amount is capped by the room left in the colony's warehouse.

Tip: If you plan to clear a lot of forest, build the Lumber Mill first. It quadruples what a Mixed or Conifer forest gives.

Clearing is not plowing #

Clearing a forest leaves open land that is not yet plowed. Plowing it is a second job. A colony's square can be cleared and plowed like any other square.

Natives #

Plowing open land never upsets the natives. Clearing forest or building a road on land a tribe claims raises its alarm, unless you pay when asked. For how much, see difficulty.md.

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8. Moving across the map #

Internally a unit's moves are counted in thirds. The cost of a step is the terrain's move cost from §1 (×3), except:

• Road at both ends: 1/3 of a move. Colony and village squares count as having a road.
• River at both ends, and the step is not diagonal: 1/3 of a move. Minor and major rivers both count.
• Entering a colony or village square never costs more than 1 move.
• Stepping between land and water with no colony at either end (landing, or boarding a ship at sea) uses up the unit's whole turn.

Running short. A unit that hasn't moved yet this turn can always make its first step, however expensive. A unit that has already moved, and has fewer points left than the step costs, gets one roll: the step succeeds with a chance of points left ÷ step cost. If it fails, the unit's turn ends where it stands.

Example: a colonist moves 1/3 along a road and then tries to climb hills (cost 2). It has 2/3 of a move left against a cost of 2, so it gets there one time in three.

Hills and mountains do not let a unit see further. Sight range depends only on the unit type and on Hernando de Soto.

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9. Fighting on terrain #

A unit's defence is multiplied by 1 + (bonus × 25%), where the bonus is the terrain's defence figure. The percentages in §1 come from this. The Colonopedia shows the same percentages.

Ambush. When natives attack one of your units outside a colony, the defender gets no terrain bonus. The attacker gets it instead, as an attack bonus. After you declare independence the same works in your favour: your troops attacking the King's troops, with neither unit in a colony, gain the terrain's defence as an ambush bonus.

Tip: Building a colony on hills is good for its ore, not its defence. Inside the colony the hills don't count. Soldiers fortified on the hills next to the colony get +150%.

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10. Other things that change land production #

These apply to worked squares (not the colony square):

• Sons of Liberty: +1 at 50% and +2 at 100% on every square that produces something. The bonus is added early, so an expert's ×2, lumber's ×2, a prime resource and Henry Hudson all double it as well. Expert farmers and fishermen get it twice instead.
• Tories: the production penalty is taken off last, so on the land it is never doubled. For when it applies, see difficulty.md.
• Native converts: +1 food, sugar, tobacco, cotton, furs or fish (not lumber, ore or silver). The +1 appears to be added even where the square's own yield is 0.
• Henry Hudson: furs from worked land ×2, applied after everything else. See founding-fathers.md.

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Curiosities and bugs found in the code #

• Bigger fishing bonuses were written but can never happen. The fish formula has steps of +2, +3 and +4 for squares with fewer than 4, 3 and 1 water neighbours. An earlier "fewer than 6" step already catches all of those, so the best coastal bonus is +1.
• A major river never adds extra food, and adds nothing extra to plowed land or a square with a road (§3).
• The Colonopedia overstates expert farmers and fishermen. It says "Expert +3". The production formula adds +2.
• Henry Hudson does not double the colony square's furs. The colony square's production is calculated separately and never checks for him.
• A depleted Silver Deposit mines better than an untouched plain mountain (§4).
• The resource list has two "Prime Timber" entries. No terrain ever uses the second one, and it has no production effect.
• Clearing gives a flat 20 lumber without a Lumber Mill. Only with the mill does the type of forest matter.
• Colonies were apparently meant to grow. The code that decides which squares a colony may work can widen the work area from the 8 surrounding squares to 12, and then to 20, as the second and third Town Hall levels are built. Neither of those Town Halls can ever be built, so the area is always 8 squares.
• Lost City Rumours are placed the same way as resources: a hash of the square's position and the map's number. There is at most one per 4×4 block, never on water or arctic.

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Sources #

All rules come from the reconstructed C source in matched/game/. The terrain figures are the data tables the game loads at start-up: UNFORESTED, FORESTED, OTHER and RESOURCE in COLTEXT0.DLL, exported to export/text/COLTEXT0.DLL/. Each terrain row holds the move cost, defence, improvement turns, an AI site value and nine yields, in that order. These tables match the DOS version's NAMES.TXT line for line. The terrain-to-resource table is read straight from the executable (segment 27, offset 0x2ca), the same table the Colonopedia draws its resource icon from. The terrain ids are in include/terrain.h, and the background is in docs/findings/terrain-table.md and docs/findings/map-planes.md. Random rolls use rand_range(lo, hi), which includes both ends.

These findings are for the Windows release. The DOS version is believed to behave the same but has not been checked line by line.