Hearts of Iron IV

Hearts of Iron IV

323 ratings
Expert AI 2.0
File Size
0.435 MB
Aug 11, 2016 @ 9:52am
May 20 @ 12:19pm
191 Change Notes ( view )

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Expert AI 2.0

Updated for 1.3.3.

This is a major AI overhaul that attempts to create an AI that plays to win, mostly by fixing the production/economy of the AI. 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 production, research, construction, variants, templates, laws, advisors, historical AI, lend-lease, naval invasions, additional in-game difficulty settings and other customisation options.

Minor features: small 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 so be careful about which mods you have enabled.
-Overview of the changes and more details here. (updated)
-Paradox forum thread.[forum.paradoxplaza.com]
-Patch notes.


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).

  • 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 made for historical focus but there should not be any game breaking issues that occur on non-historical. Historical focus in this mod does much more than just change the order in which the AI takes national focuses. It changes things like AI naval invasion logic and diplomacy in specific situations and improves their national focus use.

  • 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. Any observations in your games are welcome.

  • 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.

  • Probably compatible with minor AI mods that tweak defines or mods that add national focuses for minor countries.

  • Some mods that should be compatible: No Man's Land, Increased Resources, Standard World Map, Enhanced Peace Conference. 'Tora Tora Tora' only if Japan is not an AI. Other map mods should also work. Cosmetic mods will work.

  • MODS THAT ARE DEFINITELY NOT COMPATIBLE: any major overhaul like BICE, Kaiserreich, Modern Day mods etc. Extra tech slots for AI. Any tech tree altering mods. Any mod that tweaks the AI production in any way. Any mod that alters the national focus trees for the majors except for some specific cirumstances where the NF mod is higher up in the load order than this mod and not played by an AI.


"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. Using the sliders and/or Hard Mode is what you should do if you're not happy with the balance.

"Can this mod be made compatible with my favourite mod X?"

Yes, but not by me unless there's one that I can't play without. It would require someone to make a compatibility patch which is then enabled along with this mod and the other mod. Mods that add many technologies or laws and such can't just be plugged into the game with the expectation that the AI will somehow know how to use them and not break down. The AI has to be taught how to use them and this takes a lot of time and testing. I can give advice, explain how my mod uses the game files and such but I simply don't have time to create and maintain such compatibility patches.

"The AI only does well because of the cheats in this mod."

No. Whatever advantage you think the AI has over the player in this mod, it's still far less than the advantage you have over the AI by the virtue of possessing a brain. The "cheats" only allow the AI to do what is trivial for the player to do in 90% of cases and often the AI still doesn't quite hit the mark. The majority of this mod deals with fixing logic issues for the AI in every area of the game.

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.
Popular Discussions View All (3)
Apr 25 @ 2:36am
PINNED: Bug reports
Apr 20 @ 11:28am
PINNED: Details (updated)
Aug 22, 2016 @ 9:39am
PINNED: Patch notes
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SkelSa May 21 @ 4:28am 
@Chondrite Alright, thanks for the info! Keep up the good work!
Chondrite  [author] May 21 @ 2:04am 
@SkelSa If you run with heavy AI bonuses, it might be able to shrug the weather effects off but otherwise not really. A change like that can't be added to the mod as an option though so there would have to be a separate mod in any case.

Hard to say anything about the AI's unit management currently, it's pretty broken. What you describe could be the AI bug where on large fronts it commonly stacks all its units into one area which is fixed by reloading the game. Or it could be just "regular" AI stuff. Unlikely that I can do anything about it.
SkelSa May 21 @ 12:14am 
I've also experimented to combine this mod with the "Meaningful Weather" mod and the good thing is that there are no compatibility issues concerning overwriting code. Don't know if the AI will be affected by these changes, but in my test games everything went smooth. Have you already thought about adding an option for harsher weather or will this screw the AI too much in its current state?
I've also experienced issues with the AI overstretching its supply lines and pushing forward while it wasn't really feasible instead of distributing its units to push on all fronts. Is there something you can do or can only Paradox handle this?

Chondrite  [author] May 20 @ 10:53am 
@SkelSa Ah, I get it. I didn't actually know the tech sharing focus can give a slot. I'll have to edit the focus a bit. I guess I'll just prevent the tech sharing focus from giving an extra slot on this setting.
SkelSa May 20 @ 10:22am 
@Chondrite I just looked into it and tested GRE and PRC. First one starts in vanilla with 3, second with 2 slots. The focus "Technology Sharing" can either give you some nice boosts or a slot if you're a 2-slot minor from the start. Did you consider that? Because I just tested these two countries and GRE could only get 3 in total, while the PRC got 4...
Chondrite  [author] May 20 @ 12:56am 
@SkelSa Hmm, every minor is reduced to one slot with two extra slots from generic focuses. Since the third one is locked behind a 50 factories requirement, I figured it balances itself out and the bigger minors still get extra research.

If I'm Germany I usually have USSR on insane. It wasn't that overwhelming. Fighting against an insane Germany is probably hell though. :)

@Alma Hansen Perhaps.

@Ms. Peachez Thanks. :)
SkelSa May 19 @ 7:33pm 
I really love the option to limit the slots for minors. However, this needs some balancing since some nations which previously had 2 slots can now get 4 in total, while the nations originally starting with 3 are getting a maximum of...well...3. To sum up, I think that european minors are ok with 3 slots, but nations like Liberia don't need more than 2.
Also, have you beaten "Insane " mode? I'm currently stuck between very hard and this one but the spam is real :O
Alma Hansen May 19 @ 3:01pm 
will 1939 start be supported in the future?
Ms. Peachez May 19 @ 1:56pm 
Paradox should hire you buddy. the amount you fixed the A.I. is nuts. I played at nationalist china any my war against Japan was tough but enjoyable and historical. Had to beat them with defensive attrition until I could throw all my manpower at them when they were too weak. Took me until 1940 until I could drive them out of Korea. In vanilla I could drive out the Japos in the 1st year of the war and turn China into a super power in 2 years flat.
Alma Hansen May 19 @ 8:22am 
comfirmed ai seems to get smarter and better!! very noice:D:D:D