Pollution · Game Mechanic Compendium

Definition

Pollution simulates the by-products of industry, power and traffic as an amount held in the world, where it is made or on one shared track, and lets that amount lower what the land yields, how a city grows or how healthy its people are. Its domain is environment and its driver autonomous: between the player’s inputs, factories and traffic keep emitting and the pollution spreads, settles or is absorbed. Systemic elements spread fire or water by their own rules, and spreading blight grows on its own; pollution rises only while something emits it. Zoning demand and settlement raids read it, as one cause of low land value and as what draws attackers.

How the parts interact

The state is the pollution stored per area, square, chunk or groundwater deposit, or on CO2: Second Chance’s global track, which starts at 400 ppm. Production and traffic feed it: SimCity’s industrial zones pollute more as they grow, each Civilization smokestack is a 1% chance a turn of a polluted square, and Factorio’s boiler emits 30 a minute. Placed buildings set the rate (base building), and Civilization’s mass transit and recycling centres cost coins each turn (upkeep). Roads and pipes carry it (network building): SimCity replaces roads with rails, and Cities: Skylines II’s sewage outlets foul the water its pumps draw. Factorio’s cloud spreads 2% to neighbouring chunks every 64 ticks, and Cities: Skylines II’s ground pollution reaches a whole deposit. Land value and growth fall near the source (adjacency bonuses), polluted squares halve their yields, sick citizens cannot work, and Civilization’s score falls by 10 per square (victory points). Past a threshold come monster attacks, global warming at nine squares, or every player losing at 500 ppm. The player lowers it by cleaning (Civilization’s Settlers take four turns), by absorption in ground and trees, or by cleaner production.

Variations

Local nuisance (SimCity, Cities: Skylines II): pollution held per area lowers nearby value and health, and siting decides who bears it.
Polluted squares and a global threshold (Civilization): a chance each turn turns squares polluted, units clean them, and too many bring global warming.
Global track (CO2: Second Chance): one shared level rises with fossil plants and ends the game for all at 500 ppm.
Spreading cloud (Factorio): pollution flows chunk to chunk and is absorbed by ground, trees and enemy nests.

Components

No mechanic recurs in all five examples; the components follow the genre. Adjacency bonuses and network building appear in the two city builders, base building in Civilization and Factorio, and victory points in Civilization and CO2: Second Chance. Upkeep appears only in Civilization; markets, an end-game trigger and a semi-cooperative loss only in CO2: Second Chance; resource conversion and map-generation settings only in Factorio. No catalog mechanic covers the stored amount, its spread and absorption, cleanup by units, or a global threshold.

History and provenance

The earliest documented use cited is SimCity (1989), whose manual tracks a pollution nuisance level in every area. Civilization (1991) added polluted squares cleaned by Settlers and global warming. CO2 (2012) put a global track on a board, and its second edition, CO2: Second Chance (2018), keeps the shared loss. Factorio (2020) spreads pollution across chunks, and Cities: Skylines II (2023) separates air, ground, water and noise.

Notable examples

Notable examples, in chronological order. Notes describe how the system works in each game; the components are the mechanics it combines there and the parts its own working parts; the latest reference is a widely played game from 2020 or later.
Game	Year	Medium	Parts	Components	How the system works
SimCity Will Wright (Maxis)	1989	Video	Conditional spawn	Adjacency Bonuses, Network and Route Building	A pollution map tracks a nuisance level in every area, made mainly by industrial zones as they grow, by traffic and by coal plants. It lowers residential growth and land value and counts against the city score, high levels provoke monster attacks, and the remedies are dispersing industry and replacing roads with rails.
Civilization Sid Meier and Bruce Shelley (MicroProse)	1991	Video	Conditional spawn, Treatment, Forecast	Base Building, Upkeep and Attrition, Victory Points	A city's resources, and its population after the Automobile, give nearby squares a chance each turn of turning polluted, 1% per smokestack shown. A polluted square halves its yields and costs 10 points of score until Settlers clean it in four turns, improvements with upkeep cut the chance, and nine or more polluted squares risk global warming.
CO2: Second Chance Vital Lacerda (Giochix)	2018	Board & card	World clock, Conditional spawn, Demand	Markets, Victory Points, End-Game Triggers, Semi-Cooperative	Each decade a region whose energy needs no green plant meets gets a fossil fuel plant, which raises the global CO2 track and costs a carbon permit or a fine at the market price. Cooperative players spend victory points to push the track down at a price rising each decade, and at 500 ppm every player loses.
Factorio Latest Wube Software	2020	Video	Return to rest, Exposure, Propagation	Base Building, Resource Conversion, Difficulty Settings	Machines and boilers emit pollution into the chunk around them, and a chunk above 15 spreads 2% to each of its four neighbours every 64 ticks. Ground, water and trees absorb it, trees losing leaves where it is heavy, enemy nests absorb it to send attacks, and its settings are chosen at map generation.
Cities: Skylines II Colossal Order	2023	Video	Return to rest, Exposure, Propagation	Adjacency Bonuses, Network and Route Building	Power plants, landfills, incinerators, industry and traffic emit air, ground, water and noise pollution that lowers citizens' health, and sick citizens cannot work. Polluted ground spreads to a whole groundwater deposit so pumps draw dirty water, and filters, traffic policies and siting downwind or away from homes reduce the harm.

Provenance

Earliest documented use: SimCity (1989), video. Confidence: medium. The earliest documented use cited is SimCity, whose manual (copyright 1989) tracks pollution in every area of the city, made by industry, traffic and coal plants, lowering residential growth and land value, counting against the city score and provoking monster attacks. Earlier city and management games, and board games with a pollution track, remain unsurveyed, so the title is the earliest cited rather than a defended origin.

Sources

Maxis (Will Wright; documentation by Michael Bremer and Cliff Ellis). (1991). SimCity: The City Simulator, User Documentation, DOS Version. Rulebook Maps: Pollution Index Map; Graphs; Overall City Score; Disasters: Monster Attacks; How the Simulator Works: Pollution and Land Value, p. 45. Accessed 2026-10-30. Software and manual copyright 1989 and 1991. Pollution tracked in every area, its sources in industry, traffic and coal plants, its effect on residential growth, land value and the city score, monster attacks, and the remedies.
Sid Meier and Bruce Shelley. (c. 1991). Sid Meier's Civilization manual. MicroProse. Rulebook City display, pp. 68-69; City improvements, pp. 74-75; Environment indicator, p. 95; Civilization Score, p. 120; Planetary Caretaking, pp. 123-125. Accessed 2026-10-30. Smokestacks as a chance of pollution each turn, improvements that raise or cut it and their upkeep, halved yields, cleanup by Settlers, the score penalty, the sun indicator, and global warming at nine polluted squares.
Vital Lacerda (Giochix). (2018). CO2: Second Chance rulebook (version 0.99). Rulebook Building a power plant, p. 14; Energy Supply Phase, p. 17; Reducing pollution levels, p. 18; Competitive game: Overview and Events Phase, pp. 19-21. Accessed 2026-10-30. A pre-release version of the rules. Fossil fuel plants for unmet regional energy needs raising the global CO2 track, permits and fines at the market price, green plants replacing fossil ones, points spent to lower the track, loss at 500 ppm, and a second disaster each decade at 400 ppm.
Official Factorio Wiki. Factorio Wiki: Pollution. Wiki Pollution per chunk, its spread at 2% per 64 ticks above 15, absorption by tiles, trees and spawners, damage to trees, emission rates per building, modules, and map-generation settings.
Paradox Interactive and Colossal Order. (2023). Cities: Skylines II Feature Highlight #5: City Services. Website Accessed 2026-10-30. Polluting power plants, landfills and incinerators sited downwind and away from homes, traffic policies and air filters that cut pollution, and pollution lowering citizens' health and so workplace efficiency.
Paradox Interactive and Colossal Order. (2023). Cities: Skylines II Feature Highlight #6: Electricity & Water. Website Accessed 2026-10-30. Ground pollution spreading to a whole groundwater deposit and its recovery, sewage outlets contaminating surface water, wastewater treatment, and polluting power plants and exhaust filters.

Cite this entry

Permalink: http://localhost:4321/systems/pollution
Updated: 2026-10-30
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West, James, Jr. (2026). "Pollution." Game Mechanic Compendium, updated 2026-10-30. http://localhost:4321/systems/pollution

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