Mod «HOI4 ULTRA (Historical Industry Project)» for Hearts of Iron 4 (v1.10.1 - 1.10.4)


HOI4 ULTRA's goal is to give a historical feeling to Heart of Iron. Our ambition is to make the less changes as possible from the vanilla, but rather adapt it to a real historical balance and is meant to be played in Multiplayer.

The original goal was to give an historical repartition of the industry, but we decided to add/fix/tweak other contents we feel important.

Reasons to play or not to play ULTRA

  • You should not play ULTRA if you want memes games
  • You should not play ULTRA if you want to world conquest with [insert irrelevant minor nation]
  • You should play ULTRA if you want more historical immersion without changing the whole game
  • You should play ULTRA if you want a multiplayer game balanced toward History and realism
  • You should play ULTRA if you want to feel the power of a major country during WWII

Main feature - Industrial rebalance

The primary objective of our work was to "correct" the industrial balance in the game :
In vanilla, industry is balanced around "playability" and not around History. For the HOI4 devs team, each minor country should be "playable", the Axis should have a chance to "win", global conquest should be a possible achievment...

We don't agree with this view and want rather to play in a situation with historical settings concerning the relative power of each countries.

That's why we did a research work about the industry in the WWII timelapse in order to translate it into a mod. Our main sources are The Wages of Destruction from Adam Tooze and The Rise and Fall of the Great Powers by Paul Kennedy.

From the later, we took the concept of "war potential" for each 1936 country and translate it into ingame industry (civilian, military and dockyard). To gives some figures, the 7 Great powers have more than 90% of the world IC and the gap between the last major power (Italy) and the first (the USA) is more than 1 to 10.
To have a better repartition, we made each vanilla IC equivalent to 2 IC in the mod.

To stay in the border of plausible, we also had to change 2 keys elements : the industrial growth rate (nerfing heavily industrial snowballing, we now get a growth rate under 10% per year in 1936) and the ressources system. Coal, Iron and Bauxite were added and globaly ressources are less expensive to get (depending of the ressource) to avoid overpowered minors from lots of ressources and majors having to trade away half of their industry.

Other features

We tryed to keep things as close to vanilla as possible, so most of our work here are balance tweak for a more realist gameplay. Here is a list of some features we added or changed :

  • Combat width system (from 80 to 96 base width)
  • Division designer (10 max support + 15 max line)
  • Many focus/decisions/events/ideas tweaks
  • Some new events/decisions/focus/ideas including surrender events chains for every majors and a Enigma/ULTRA feature
  • Research and equipment balance (including the addition of some plane models and a land doctrines overhaul)
  • Naval overhaul "Naval Rework" mod integrated
  • Integration of QoL mods

Mod checked on game version: 1.10.1 , 1.10.2 , 1.10.3 , 1.10.4

  • A large amount of new content.

Version 31.10.20 for Hearts of Iron 4 (v1.10.1)

  • Mod updated for game version 1.10;
  • A large amount of new content.


Version 25.09.20 for Hearts of Iron 4 (v1.9.0 - 1.9.3)

  • Various improvements and fixes.


Version 10.07.20 for Hearts of Iron 4 (v1.9.0 - 1.9.3)

  • Various improvements and fixes.


Version 29.06.20 for Hearts of Iron 4 (v1.9.0 - 1.9.3)


  • Resistance is more painfull and need more garrison
  • XP for divisions and leaders is harder to get
  • XP threshold are now exponentials instead of linears for units
  • Cavalry rebalanced to be more in line with light infantry
  • Terrain effects rebalanced
  • Slight tank rebalancing and additions of a few variants


  • Events closing automaticaly buildings in case of resources shortages will now target occupied territories in priorities
  • New decisions to close occupied resources consuming buildings without any cost
  • Decisions to reopen resources consuming buildings no longer cost pp but have 10 days timers instead
  • Tanks divisions withtout enough infantry will suffer maluses in every terrains, plains included. Encourage combined arms.
  • Implemented Amphibious tanks, available for a limited amount of nations, to be completed later
  • Updated Soviet OOB and stockpiles
  • Added more option in the tank designer


  • Removed the cavalry duplicated bonuses in Infantry techs


Version 29.05.20 for Hearts of Iron 4 (v1.9.0 - 1.9.2)

  • Minor bufixes and balance changes.


Version 02.05.20 for Hearts of Iron 4 (v1.9.0 - 1.9.2)

  • A large number of new content;
  • Various fixes and improvements.


Version 26.03.20 for Hearts of Iron 4 (v1.9.1)


How to install mod?

To install the mod for the game Hearts of Iron 4, unpack the contents of the archive to the folder Documents\Paradox Interactive\Hearts of Iron IV\mod and enable the modification in the launcher.

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