Iron Nest World War

Iron Nest: World War

When the Iron Nest Comes to Hearts of Iron IV

When the five-thousand-ton dieselpunk war machine from IRON NEST: Heavy Turret Simulator tears through time and space, the thunder of artillery from an alternate-history Spain on the brink of civil war finally reaches Hearts of Iron IV.

High Command continues to issue orders through the teleprinter. Coordinates, aerial photographs, propellant calculations and firing solutions still determine every shot. Now, research facilities study the steel colossus, military factories attempt to reproduce its guns and mechanical legs, and general staffs consider how it might be used in a true world war.

Iron Nest: World War is an unofficial fan-made crossover mod for vanilla Hearts of Iron IV. It brings the walking turret, dieselpunk atmosphere and High Command directives of IRON NEST into HOI4’s Special Projects, production, support companies, regional deployment, railway artillery and Ship Designer.

From a classified blueprint to an artillery system spanning land, railway and sea—Operator, High Command is waiting for your firing solution.

Unlocking the Iron Nest

• Research the vanilla Railway Gun technology. The vanilla technology tree is not replaced.

• The Chief Designer submits the Iron Nest General Project report and grants a one-time 50% Land Special Project Breakthrough progress reward.

• Begin the Iron Nest General Project at a Land Warfare Facility for 1 Land Breakthrough Point.

• The project takes approximately 250 days, although scientists, facilities, supply and prototype events may change the actual duration.

• Completion unlocks the Solo and Duet Iron Nests, the 280 mm Steel Rain system, their support companies and railway guns, and delivers one Duet Railway Gun prototype.

Three 800 mm Variants

• Solo: A single-barrel configuration with the lowest firepower and production cost.

• Duet: The balanced standard twin-barrel configuration.

• Trio: An extreme triple-barrel configuration with the greatest firepower and logistical burden.

• Trio Synchronized-Loading Trials require 50 Political Power, 50 Army Experience and 120 days, unlocking the Trio equipment, divisional support company and railway gun.

Divisional Iron Nest Support

• All three variants can serve as Divisional Support Companies. A division may field only one Iron Nest variant at a time.

• They provide +5% Defense and +5% Breakthrough to infantry, motorized and mechanized formations.

• Solo, Duet and Trio provide 0.5, 1 and 1.5 Reconnaissance, together with 300, 400 and 500 Additional Collateral Damage.

• They receive specialized attack modifiers for deserts, rivers, amphibious operations, plains, forests, hills, mountains, jungles, marshes, urban terrain and forts.

• Forests, urban terrain and forts also provide movement bonuses, with terrain performance increasing from Solo to Trio.

The 280 mm Steel Rain

• A lighter twin-barrel walking-artillery derivative of the General Project.

• Steel Rain serves exclusively as a Regimental Support Company and can be used alongside a divisional Iron Nest company.

• It includes dedicated equipment, a regimental support company and a railway-gun model.

• Its support company receives +3% Attack and +3% Movement across the major terrain types.

• Steel Rain equipment is also required for regional fire-support emplacements.

Regional Fire-Support Positions

• Select an owned and controlled state, then spend 25 Political Power and 3 Steel Rain equipment.

• After 7 days, friendly forces receive +5% Attack, +5% Defense, +5% Breakthrough, +5% Entrenchment Speed and +5 Maximum Entrenchment in that state.

• The bonus applies only to the deploying country.

• The position can be recovered in 3 days, returning all 3 Steel Rain equipment.

• Deployment decisions and map markers can be displayed together, separately or hidden.

Railway Artillery and Engineering Programs

• Solo, Duet and Trio Railway Guns provide 37.5, 75 and 112.5 bombardment.

• All Iron Nest Railway Guns have a 35-map-pixel support radius, approximately 248.5 km.

• Steel Rain provides 25 bombardment and a 30-map-pixel radius, approximately 213 km.

• Railway Artillery Production Rationalization: 100 Political Power, 100 Army Experience and 180 days. All vanilla, Iron Nest and Steel Rain Railway Guns receive −10% production cost.

• Mobile Iron Nest Support Group: commit 25 Iron Nest equipment for 30 days to gain +3% Army Attack, +3% Army Defense and +5% Breakthrough.

• Reliability Improvement Program: 75 Political Power, 50 Army Experience and 120 days. The 25% multiplicative bonus raises Iron Nest and Steel Rain reliability from 80% to exactly 100%.

Naval Artillery

• The General Project unlocks a Solo 800 mm naval gun for conventional heavy-battery slots.

• Super-Heavy Naval Mounting Research requires 50 Political Power, 100 Navy Experience and 180 days.

• Completion unlocks Solo, Duet and Trio 800 mm super-heavy naval turrets.

• The naval program and Army Trio trials use independent technologies and may run simultaneously.

Localization, Compatibility and Requirements

• Current version: v.1.1.0

• Supported version: Hearts of Iron IV 1.19.*

• Fully localized in English and Simplified Chinese.

• No Step Back is required for Railway Gun content.

• Man the Guns is recommended for the naval-turret content.

• The mod does not replace the vanilla technology tree or shared script-enum files.

• Conflicts may occur if another mod overwrites the same Special Projects, units, equipment, ship modules, decisions or interface files.

Fan-Made Project Disclaimer

This is an unofficial fan-made crossover bringing IRON NEST: Heavy Turret Simulator into Hearts of Iron IV. It is not officially affiliated with the developers of IRON NEST or with Paradox Interactive.

All related titles, imagery, trademarks and intellectual property belong to their respective owners. If you enjoy the design, atmosphere and super-heavy artillery of the Iron Nest, please consider visiting and supporting the original game.