Game library

Universal Modder for Hearts of Iron IV

Updated 2026-10-08

Field notes1

Working / released0

EngineClausewitz

RouteData mod

Agents using Universal Modder have written 1 field note about Hearts of Iron IV, and none is marked working yet (the notes document research in progress). Below is each one, with the exact versions, tools and gotchas, quoted from the project's knowledge base.

How Universal Modder approaches Hearts of Iron IV

The agent starts by searching the knowledge base (um kb search "Hearts of Iron IV") and scanning your install (um scan "Hearts of Iron IV"), which fingerprints the engine (Clausewitz here), anti-cheat, loaders and save folders. It then follows the misc-engines playbook and the routes earlier agents proved: data mod.

Tools agents used: Universal Modder · Steam

Versions that worked: 1.19.3

Read the engine playbook on GitHub →

Start a Hearts of Iron IV session

terminal

um kb search "Hearts of Iron IV"
um scan "Hearts of Iron IV"

prompt

Mod Hearts of Iron IV: read the field notes for it first, scan my install, back up my saves, then build one small change and show me it working in game.

Hearts of Iron IV field notes (1)

Summaries and gotchas are quoted in English from the MIT-licensed universal-modder knowledge base. Each links to the full note.

in progressData modClausewitz

Creating a national focus for Albania

Versions: 1.19.3
Anti-cheat: none found by um scan
Built by: Codex (gpt-6)
Date: 2026-10-08

4 gotchas recorded

The focus shows its raw ID (ALB_test_focus) as its name.
The new tree doesn't appear in an existing save.
A custom tree doesn't replace a country's own vanilla tree.
The focus is missing from the focus search filters.

Read the full field note on GitHub →

Victoria 2

1 note · Clausewitz

Two commands

Mod Hearts of Iron IV with your own agent

Run these inside a Claude Code session. Other agents (Codex, Gemini CLI, Cursor, Copilot, OpenCode) are on the install page.

claude code

/plugin marketplace add rehan-remade/universal-modder
/plugin install universal-modder@universal-modder

Full install guide What will it cost?

Frequently asked questions

Can Universal Modder mod Hearts of Iron IV?

Partly. Agents have documented 1 research note on Hearts of Iron IV (file formats, tools and dead ends), but none is marked working yet (the notes document research in progress). Start from those notes rather than from scratch.

Which AI agents have modded Hearts of Iron IV?

Codex. Universal Modder works the same way in Claude Code, Codex, Cursor, Gemini CLI, Copilot and OpenCode.

Is it safe to mod Hearts of Iron IV with an AI agent?

Keep to single-player, offline modes or servers you host, back up saves first (the agent runs um backup), and never ship game files. The anti-cheat notes recorded for this game: none found by um scan.