Expert AI 4.0

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Author: Chondrite
Last revision: 24 Jan at 14:59 UTC


Compatible with 1.5.*

Do you want to play vanilla HOI IV but can’t find the challenge you need because the AI plays the game at a beginner level? This mod is for you. Nearly everything about the AI that is possible to mod has been overhauled (with over fifty thousand lines of script added) to create a more efficient AI.

That includes division designs, division production, equipment production, variants, research, diplomacy, construction, naval invasions, ideas and more. In other words how well the AI manages its country overall. There is absolutely massive room for improvement in these areas in the vanilla game. What is NOT fixed is how the AI moves its divisions, fleets and such except for tweaks here and there. This area is largely unmoddable.

Other than just making the AI more efficient, this mod also adds completely new AI features such as:
  • A scripted AI army focus system that allows any AI to choose from a wide range of different strategies and to logically prioritise research and variant design accordingly instead doing the same thing every game. There are over 400 template variations for the AI to design towards when creating divisions which gives it adaptability and adds replayability to the game.
  • New military coordination decisions for the player that allows you to influence what your allies do: launch coordinated naval invasions, change production priorities, check their stockpiles, coordinate lend-lease.

There is also a flexible in-game configuration tool (CTRL-SHIFT-O) that allows you to customise the difficulty and the AI in various ways at any point in the game:
  • Change certain AI behaviour or game balance.
  • Customise any country’s build strategy (army, air, navy) from the specifics of template composition and width to land doctrine paths and fleet composition.
  • Add various different types of difficulty settings from simple bonus modifiers to scaling modifiers and even free division and equipment spawning until you find the challenge you need.

Some gameplay aspects have been slightly rebalanced to provide more interesting games (see the mod documentation here).

This mod works best with historical focuses. The overall progression of the game has been made more historical and the AI is more efficient with national focuses. Playing with all DLCs is highly recommended but not absolutely necessary.

Other mods:

-Expert AI: Expanded Technologies.
-Allied Construction Projects
-Strategic View Adjustments

Compatible mods.

Paradox forum thread.[]

Patch notes.

Suggestions & feedback.

Bug Reports.

Read before using:
  • If you are an experienced player and want a challenge especially as a major, you should still give the AI bonuses (see recommended settings here).
  • The AI takes certain shortcuts to be on a more level playing field with the player (listed in the ‘details’ thread). This mod is about having a competetive AI right now and not after a couple of major DLCs – these shortcuts allow the AI to do things that are simple for an experienced player to manage rather than give it an unfair advantage over the player.
  • This mod is meant to be played with historical focuses enabled but there should not be any game breaking issues that occur on non-historical. Historical focus setting in this mod does more than just changes the order in which the AI takes national focuses and which decisions it makes in events.
  • This mod is not balanced around playing with minor nations. If going on a conquest spree with minors is impossible or at least much harder, then it is working as intended.
  • 1939 start is not supported due to how much work it is to adapt to this mod.

  • Not achievement compatible.
  • It is recommended that you play with all DLCs but it is not absolutely necessary.
  • Multiplayer compatible when every player has this mod enabled.
  • This is a major overhaul that edits nearly every important file, therefore this is not compatible even with non-AI overhauls or mods that add or change technologies, advisors, new equipment etc. Compatible mods.


"Does this help performance by fixing AI division spam?"

The AI won’t spam thousands of divisions in the late game, so yes. There is however a performance cost to all the additional AI scripting in this mod. In short, the game is a little slower from the beginning but lags out less during the late game.

"I picked Germany, set sliders to max and steamrolled all of Europe/world by 1939."

This is a sandbox game so you can play any way you like. However there are several problems with this: 1) Germany is by far the easiest nation, 2) the sliders only very marginally help the AI (so use more buffs through the EAI config), 3) there’s a reason why many MP games use a massive list of house rules. The game is completely unbalanced without them and if human players can’t deal with it then the AI sure as hell can’t.

"Something ahistorical happened on historical mode."

It’s not my intention to force the game to play out exactly historically whether it’s Germany always losing by 45 or China not getting annexed by Japan. Customise the difficulty if you want to see some nation perform better.

"Can you make this compatible with my favourite mod X?"

It is unlikely that I will integrate other mods into Expert AI (or the other way around) for the time being. This mod is created around the vanilla Hearts of Iron 4 with painstaking effort to make an AI that understands how to play efficiently with the tools that it has.


Inspired by the ‘AI Research and Division Tweaks’ mod.

Thanks to everyone who have given feedback, made suggestions or reported problems.

Thanks to the following people for testing, contributions or specific ideas: Yossarian, VDNKh, RunsOnDiesel, Zijistark, Axe99, Locomotive, Fabius.

French translation by Scribio ->