Expert AI 2.0

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Author: Chondrite
Last revision: 22 Aug at 17:15 UTC


Updated for 1.4.2

This is a major AI overhaul that attempts to create a more competetive AI primarily by improving every aspect of the AI’s management of its country. This is first and foremost for those who enjoy min-maxing and challenging themselves and want the AI to put up a fight beyond what simply dumping bonus modifiers on the AI can achieve.

Ultimately the goal is to make the game have a decent challenge when playing as any major and additionally to make the historical mode actually behave in a more historical manner.

Main features: overhauled AI management of production, research, construction, variants, templates, laws, advisors, historical AI, lend-lease, naval invasions. An in-game customisation event that allows you to reconfigure parts of the AI or create as much difficulty as you want.

Minor features: tweaks to land, naval and air AI. Dozens of fixes to specific AI issues.

Do NOT use this mod without reading the rest of this page.

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.

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 (note that the in-game sliders aren’t enough in my opinion if you play someone like Germany). 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). These are in place because there is currently no proper way to make the AI handle certain things like templates well enough. If in the future modding support is implemented to handle these areas in a better way, I will remove the shortcuts. All of these are made to be as close to what the player can achieve in game but sometimes that isn’t possible in which case I always choose a way that makes the game more challenging rather than leaving the AI handicapped.
  • 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.
  • 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.
  • MODS THAT ARE DEFINITELY NOT COMPATIBLE: any major overhaul like BICE, Kaiserreich, Modern Day mods etc. Any tech tree altering mods.


"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 (go double or triple their industry), 3) there’s a reason why many MP games enforce historical progression among many other 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. It would be nice if the game played out that way most of the time but there’s always something random that happens in every game (though anything absurd happening is usually a bug and you should let me know about it) and the game itself is not balanced very historically. 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 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. Other mods tend to change all sorts of things in the game that would require adjusting the AI to work properly with them and not only would it take a lot of scripting and testing but also playing those mods to find out how they work before I can make the AI play with them well. However, feel free to create a compatibility patch yourself if you’re wiling to do most of the work (and if you need some pointers with how to achieve this, you can ask me).

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.

Russian localization by santyrion.