Fire

_{Focus Areas · Design document §3}

Available from: Game Start

12 breakthroughs — CORE 5 · STANDARD 2 · UNCOMMON 2 · RARE 1 · UNIQUE 2 — Primitive – Medieval

Builds on: Foraging (1) · Stonework (1) · Observation (2) · Social Organization (1) · Mining (1) · Metallurgy (2) · Warfare (1)

Leads into: Foraging (1) · Stonework (1) · Mining (1) · Metallurgy (4) · Warfare (2) · Textiles & Materials (1) · Mechanics (1) · Chemistry (1) · Optics (2) · Aeronautics (1)

_{The numbers count prerequisite links between this focus and the other. How to read the tables.}

Overview

ID	Breakthrough	Tier	Era	Prerequisites
F01	Controlled Fire	CORE	Primitive	None
F02	Kiln Construction	CORE	Primitive	F01
F03	Charcoal Production	CORE	Primitive	F01
F04	Smelting Discovery	CORE	Primitive	F03 + S04 (Ore Identification)
F05	Signal Fires	STANDARD	Ancient	F01 + SO03 (Tribal Law)
F06	Greek Fire	UNCOMMON	Classical	F03 (Charcoal Production — wood tar) + O08 (Geological Observation — sulphur)
F07	Advanced Pyrotechnics	CORE	Medieval	F03 + O08 (Geological Observation — sulphur) + MI08 (Saltpeter Mining — the oxidiser)
F09	Controlled Burn Agriculture	UNCOMMON	Primitive	F01 + G02 (Seed Saving)
F10	Thermal Lance	RARE	Ancient	F01 + F03 + ME-B (Bellows)
F11	Volcanic Forge Tradition	UNIQUE	Classical	F03 + ME-B (Bellows) + Volcanic region
F15	Signal Fire Network	UNIQUE	Ancient	F05 (Signal Fires) + WA06 (Fortification Design) + Mountain/highland or Many neighbors biome
F16	Turbary	STANDARD	Ancient	F03 (Charcoal Production) + Marsh in territory

Prerequisite map

flowchart LR
  n_F01["F01 Controlled Fire"]:::CORE
  n_F02["F02 Kiln Construction"]:::CORE
  n_F03["F03 Charcoal Production"]:::CORE
  n_F04["F04 Smelting Discovery"]:::CORE
  n_F06["F06 Greek Fire"]:::UNCOMMON
  n_F07["F07 Advanced Pyrotechnics"]:::CORE
  n_F10["F10 Thermal Lance"]:::RARE
  n_F11["F11 Volcanic Forge Tradition"]:::UNIQUE
  n_F16["F16 Turbary"]:::STANDARD
  n_F05["F05 Signal Fires"]:::STANDARD
  n_F15["F15 Signal Fire Network"]:::UNIQUE
  n_F09["F09 Controlled Burn Agriculture"]:::UNCOMMON
  n_F01 --> n_F02
  n_F01 --> n_F03
  n_F03 --> n_F04
  n_F01 --> n_F05
  n_F03 --> n_F06
  n_F03 --> n_F07
  n_F01 --> n_F09
  n_F01 --> n_F10
  n_F03 --> n_F10
  n_F03 --> n_F11
  n_F05 --> n_F15
  n_F03 --> n_F16
  classDef CORE fill:#dbeafe,stroke:#1d4ed8,color:#0b1b3b
  classDef STANDARD fill:#f1f5f9,stroke:#64748b,color:#0f172a
  classDef UNCOMMON fill:#dcfce7,stroke:#15803d,color:#052e16
  classDef RARE fill:#fef3c7,stroke:#b45309,color:#3b2005
  classDef UNIQUE fill:#fae8ff,stroke:#a21caf,color:#3b0a3f

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_{Prerequisites within this focus. Box colour is the tier (blue CORE, grey STANDARD, green UNCOMMON, amber RARE, purple UNIQUE); dotted arrows are alternatives (“or”); a line can pass behind another box, so follow it from its start. 8 of these 12 breakthroughs also need breakthroughs from other foci, which the overview above lists.}

Breakthroughs

F01 · Controlled Fire

• Tier: CORE · Era: Primitive
• Prerequisites: None
• Unlocks: ⟨[+1 Production] [in all cities]⟩ (work by firelight); ⟨[+1 Food] from [Tundra] tiles [in all cities]⟩ (warmth). The foundation: fire makes every settlement a little more productive and the cold lands habitable.
• Notes: Foundation of civilization.
• Leads to: F02 Kiln Construction, F03 Charcoal Production, F05 Signal Fires, F09 Controlled Burn Agriculture, F10 Thermal Lance, G04 Fermentation, MC07 Hero's Aeolipile (Early Steam), CH04 Distillation, AE01 Hot Air Balloon

F02 · Kiln Construction

• Tier: CORE · Era: Primitive
• Prerequisites: F01
• Unlocks: Shrine (and the Maya Pyramid it is replaced by). ⟨[+25]% City Strength from defensive buildings⟩ — walls of fired brick. Kiln heat — fired pots, glazes, fired brick — leads on to Glassmaking (OP01) and Geopolymer Concrete (S09).
• Leads to: S09 Geopolymer Concrete, TX10 Paper Making, OP01 Glassmaking

F03 · Charcoal Production

• Tier: CORE · Era: Primitive
• Prerequisites: F01
• Unlocks: ⟨[+25]% Production when constructing [Melee] units [in all cities]⟩ — hotter fires, harder blades. The hotter fire that makes smelting (F04) and iron (ME04) possible. Wood tar, the kiln's by-product: ⟨[-25]% maintenance on road & railroads⟩; ⟨[+10]% Strength <for [Water] units>⟩ — tarred roads, caulked hulls (Pitch and Tar, merged here in v3.101).
• Notes: Key bridge to Metallurgy.
• Leads to: F04 Smelting Discovery, F06 Greek Fire, F07 Advanced Pyrotechnics, F10 Thermal Lance, F11 Volcanic Forge Tradition, F16 Turbary, MI13 Wood Gas Production, ME04 Iron Smelting, ME05 Steel Production, ME08 Blast Furnace, OP01 Glassmaking

F04 · Smelting Discovery

• Tier: CORE · Era: Primitive
• Prerequisites: F03 + S04 (Ore Identification)
• Unlocks: Unlocks Metallurgy focus. ⟨[+1 Production] from [Copper] tiles [in all cities]⟩ and ⟨[+1 Gold] from [Gold Ore] tiles [in all cities]⟩ — the ores Ore Identification (S04) revealed become worth working.
• Notes: The moment someone puts green rock near hot charcoal. Transformative.
• Leads to: ME01 Copper Working

F05 · Signal Fires

• Tier: STANDARD · Era: Ancient
• Prerequisites: F01 + SO03 (Tribal Law)
• Unlocks: Signal Fireⁿ [improvement on Hill; 5 turns; ⟨[+1] Sight⟩; ⟨Gives a defensive bonus of [20]%⟩]. An early-warning post on high ground.
• Leads to: F15 Signal Fire Network

F06 · Greek Fire

• Tier: UNCOMMON · Era: Classical
• Prerequisites: F03 (Charcoal Production — wood tar) + O08 (Geological Observation — sulphur)
• Unlocks: Fire Shipⁿ [unit, Melee Water; cost 70; mv 4; str 14; ⟨[+50]% Strength <when attacking>⟩; ⟨[+50]% Strength <vs [Water] units>⟩]; ⟨[+25]% Strength <for [Siege] units> <vs cities> <when attacking>⟩. Pine pitch, sulfur and a siphon — no petroleum required. Also discoverable through Warfare or Seafaring focus.
• Notes: Historical Byzantine weapon.
• Leads to: WA12 Greek Fire Naval Warfare

F07 · Advanced Pyrotechnics

• Tier: CORE · Era: Medieval
• Prerequisites: F03 + O08 (Geological Observation — sulphur) + MI08 (Saltpeter Mining — the oxidiser)
• Unlocks: Fireworks Groundⁿ [70/1; +1 Culture, +1 Happiness; requires Saltpeter]. Prerequisite for Gunpowder (WA10) unless GUNPOWDER_ABSENT.
• Leads to: WA10 Gunpowder

F09 · Controlled Burn Agriculture

• Tier: UNCOMMON · Era: Primitive
• Prerequisites: F01 + G02 (Seed Saving)
• Unlocks: ⟨[-50]% construction time for [Remove Forest] improvements⟩ and ⟨[-50]% construction time for [Remove Jungle] improvements⟩; ⟨[+25]% Yield from pillaging tiles⟩ (burning what you clear). Land is opened fast — and what is burnt gives back.

F10 · Thermal Lance

• Tier: RARE · Era: Ancient
• Prerequisites: F01 + F03 + ME-B (Bellows)
• Unlocks: ⟨[+30]% Production when constructing [All] wonders [in all cities]⟩. Stone shaped by directed heat.
• Notes: Speculative: what if directed-heat tools were developed early?

F11 · Volcanic Forge Tradition

• Tier: UNIQUE · Era: Classical
• Prerequisites: F03 + ME-B (Bellows) + Volcanic region
• Unlocks: Volcanic Forgeⁿ [replaces Forge; 120/1; +2 Production; ⟨[+1 Production] from [Volcanic] tiles [in this city]⟩; ⟨[+15]% Production when constructing [Land] units [in this city]⟩; ⟨Must have an owned [Volcanic] within [2] tiles⟩]. Civ unique: ⟨[+1 Production] from [Volcanic] tiles [in all cities]⟩ — the more vents you hold, the more you forge.
• Notes: Icelandic/Japanese tradition of forging with Earth's own heat.

F15 · Signal Fire Network

• Tier: UNIQUE · Era: Ancient
• Prerequisites: F05 (Signal Fires) + WA06 (Fortification Design) + Mountain/highland or Many neighbors biome
• Unlocks: Signal Towerⁿ [20/0; ⟨[+10]% Strength for cities⟩ (applies to this city)]. Civ unique: ⟨[+20]% Strength <for [Military] units> <when defending> <in [Hill] tiles>⟩ — the high ground warns and holds.
• Notes: Greek phryctoriae, Chinese beacon towers, Gondor. Relocated from the former Communications focus.

F16 · Turbary

• Tier: STANDARD · Era: Ancient
• Prerequisites: F03 (Charcoal Production) + Marsh in territory
• Unlocks: Peat Cuttingⁿ (improvement; terrainsCanBeBuiltOn: [Marsh]; 6 turns; ⟨[+2 Production]⟩; ⟨Does not need removal of [Marsh]⟩) — fuel burned where it lies. A bog can now be drained (the Aqueduct's flood control, WM02) or cut. A worked Peat Cutting also counts as a fuel tile for a Charcoal Kiln (ME08), and lets a city's Distillery make Whisky (CH04). Needs a Marsh in the civilisation's territory: a people with no bogs never learns to burn them. (Named apart from its improvement under the filter discipline of §7.0, since the kiln and the Distillery both filter on [Peat Cutting].)
• Notes: Pliny described the Chauci burning peat in the first century; the right to cut it, turbary, is one of the traditional common rights of English law.