hearts-of-iron-4 game sourced
Hearts of Iron IV
A World War II grand strategy game starting in 1936 or 1939 in which the player builds factories, turns resources into equipment, designs divisions, follows a national focus tree, and directs fronts and battle plans across land, sea, and air.
core loop
pick national focuses and spend political power -> assign civilian factories to construction and military factories to equipment -> design and train divisions -> draw fronts and battle plans -> divisions fight on supply, terrain, and weather -> capitulate rivals or hold
design notes
HOI4 separates the industrial war from the field war: civilian factories build capacity and military factories turn resources into equipment, so divisions fight only as well as stockpiles and supply allow. Battle plans let the player act at army-group scale and leave division movement to the AI. National focus trees are the authored branching layer that steers countries toward historical or alternate paths, while battles resolve from unit statistics (proposal stat-combat-resolution).
relations
17 stored edgesDelegation to AI managers
The player draws front lines and offensive arrows for armies under generals, and the AI moves divisions to carry out the battle plan; divisions can also be ordered directly.
Modular assembly
Division templates combine battalions (infantry, tanks, cavalry, motorized, mechanized) and support companies, and the mix sets combat statistics and equipment needs; tank, ship, and plane designers added by DLC apply the same idea to equipment.
Supply lines
Supply hubs connect to the capital by railway, with hub capacity set by railway level and limited by the weakest link; supply falls off per province from the hub, and divisions at 35% supply or less suffer attrition and combat penalties.
Tech tree
Research runs in parallel slots, and each country has a national focus tree in which one focus at a time is completed for bonuses such as extra factories or events; at launch only Germany, the UK, the USSR, and the US had unique trees.
Faction diplomacy
Countries join factions and guarantee others; world tension from 0 to 100 gates what democracies can do.
Modding API
Script files define focus trees, events, and units; total conversions such as Kaiserreich rebuild the scenario.
Policy toggles
Mobilization, conscription, and trade laws and ministers are bought with political power.
Political capital
Political power accrues over time and is spent on laws such as mobilization, conscription, and trade, on ministers, and on decisions.
Production chains
Military factories turn strategic resources into equipment on production lines, dockyards build ships, and civilian factories build infrastructure and handle trade.
Stability and unrest
Ideology popularity among democratic, communist, fascist, and non-aligned groups shifts the government and can end in civil war.
Statistical combat resolution
Divisions fight in hourly combat rounds comparing attacks against defense or breakthrough, draining organization and strength under terrain, weather, and supply modifiers.
Territorial control
States are core or non-core, armies occupy enemy states during war, and peace conferences transfer ownership.
War score and peace terms
When a country capitulates, winners take turns spending peace conference points on annexation, puppets, and other demands.