Expert AI 2.0

If you liked this mod, please rate it up on Steam Workshop page.
Author: Chondrite
Last revision: 3 Dec at 11:06 UTC


Compatible with 1.4.2

This is a major AI overhaul that attempts to create a more competetive AI. Half the game is about how well you manage your country (research, industry, production etc.) – this is the primary focus of this mod as it is the most moddable aspect of the AI. This mod includes over 70k added lines of script for the AI that allows the AI to take advantage of the smaller nuances of the game mechanics and creates replayability by allowing the AI to change the type of army it builds from game to game and to adjust its priorities accordingly.

This mod is created for historical play (that means playing with historical focus on and not going overboard with exploits and AI abuse) but it is not a requirement. AI diplomacy has been edited to create a more historical flow to the game when it comes to wars and other major events but effectiveness comes before a historical AI in other areas.

  • Expanded Technologies. More late game techs as well as rebalancing of the game, especially in areas where the AI is weak.

Main features:

-Overhauled AI management of production, research, construction, variants, templates, laws, advisors, historical focuses, lend-lease, naval invasions, volunteers.

-In-game customisation event that can be accessed at any point in the game which allows you to: reconfigure AI army build and research priorities, add bonuses for the AI or specific countries in several ways, adjust some AI behavior and make other tweaks to create the scenario you want to play.

-New diplomatic AI behavior. AI may now react to unwarranted aggression.

Minor features:

-tweaks to land, naval and air AI.

-Dozens of fixes to specific AI issues.

This mod has extremely limited compatibility with other non-cosmetic mods due to the extensive rework of the AI. Incompatible mods will likely result in a broken AI even if the game doesn’t crash.

How big of a difference does the mod make? Here is an army/economy comparison between Expert AI and vanilla to give you a rough idea:

Compatible mods.

Paradox forum thread.[]

Patch notes.

Suggestions & feedback.

Bug Reports.

Mod details.

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). HOWEVER, this is for players with hundreds of hours played who already know the game in and out. Otherwise the best way to start is to play a game with no bonuses at all and then increase difficulty if needed.
  • 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 is not supported due to how much work it is to adapt to this mod.
  • There are A LOT of aspects that I have tweaked and it’s possible that I have made an odd choice somewhere. If you have suggestions on effective strategies that could be used by the AI, let me know.

  • Not achievement compatible.
  • 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. I usually focus on improving the AI for countries that don’t perform as well as they historically should but I will never give them free troops or factories and such. 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.

Want to use some part of this mod in your own public mod? Ask for permission.


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, Stjern, Scrublord, Zijistark, Axe99, Locomotive, Fabius.

Russian localization by santyrion. Ahistorical AI focus logic by mrkettyo.