A complete editor for Hearts of Iron IV and Millennium Dawn focus trees — the visual canvas, the real game data, structured authoring, validation and byte-identical export, plus an AI bridge that can build the tree for you.
A node-graph editor that mirrors how a focus tree actually looks in-game.
Every focus is a bracket-framed icon with a name plate below it — the same vertical layout HOI4 draws. Prerequisite lines route orthogonally in steel-blue; mutually-exclusive focuses are joined with a red link. You can judge the in-game look while you build.
Drag from a node’s bottom port onto another focus to make it a prerequisite — a live dashed preview routes as you go, then snaps to a clean orthogonal edge. Drag onto empty canvas to spawn a connected child in one motion.
Context menus on nodes, edges and empty canvas: add a child, create a focus here, delete a focus, or delete a connection (prerequisite or mutex).
Rubber-band select several focuses and delete them at once. Prerequisite and mutex references to anything you remove are cleaned up automatically — no dangling links.
A search box filters the focus list and highlights matches on the canvas with an amber ring while dimming everything else — find any focus in a big tree instantly.
New focuses are auto-prefixed with your country tag (e.g. LBA_…), following HOI4 convention, however you create them.
The actual game art and data, detected and indexed for you.
Qt can’t read HOI4’s DDS art, so Focus Forge ships its own pure-Python DDS decoder (uncompressed + DXT1/3/5). Nodes render the real icons — with a clean bracketed abbreviation as a fallback when one can’t be resolved.
Browse thousands of base-game and Millennium Dawn focus icons in a searchable thumbnail grid and assign one in a click, with a live preview in the inspector.
Finds Hearts of Iron IV and Millennium Dawn from Steam’s own config — across any drive, custom library folders, or non-default installs — and locates the MD workshop content automatically.
States, technologies, buildings, modifiers, country tags, ideologies and parties are all read straight from your install (honouring MD’s replace_path rules), so every dropdown reflects your actual game.
Politics, leaders and flags — pre-filled from Millennium Dawn.
Auto-fills the country’s real MD starting popularities and badges the ruling party “in power”. Adjust freely, with a live total and a one-click reset to the MD values.
Pick from your country’s real MD leader portraits. Traits are searchable, categorized, and show their bonuses on hover. Import a custom portrait and the export auto-generates the sprite for it.
Previews MD’s current flag for your tag. Import a custom flag (TGA/PNG/DDS) — Focus Forge writes the game-correct TGA and DDS formats on export, since Qt can’t.
Start a launcher-ready submod, or edit an existing tree.
Writes a launcher-ready Millennium Dawn submod — descriptor, folder skeleton and dependencies — into your mod folder on first export, so it appears in the HOI4 launcher with no boilerplate.
Load a country’s existing focus tree as an editable project — 155 trees across base game and MD. Relative positions are resolved to absolute coordinates, titles are localised, and the real icons come along.
Trees shared by several countries surface under each tag, and MD’s replace_path is honoured so vanilla WW2 trees never leak into the list.
For the many countries with no dedicated MD tree (Mexico, Morocco, Portugal…), seed an editable copy of the generic tree, namespaced under your tag.
Your editable .focusforge.json lives in a workspace; one-click Export to Mod materialises the HOI4 files. Save and Export stay cleanly separate.
Catch problems before the launcher does — then export exactly right.
Flags missing prerequisites, dependency cycles and overlapping focus positions as you work.
Checks the things that quietly break a mod: empty tree id, export filename, localisation prefix, country settings, and event-namespace mismatches — and lists the blocking issues before you export.
Generates the HOI4 .txt focus tree, localisation .yml (with BOM), ideas, events, country history and localisation, plus flag TGAs and portrait DDS files — produced byte-for-byte the way HOI4 expects.
Build and edit your tree by asking an AI assistant.
Connect an assistant like Claude over a local connector and describe what you want — “add a four-focus war-economy branch with a mutually-exclusive choice”. The focuses, ideas and events build themselves on the canvas.
Everything the AI does is ordinary editing — visible live, and fully undoable. Anything it changes counts as unsaved, so closing still prompts you to save.
The bridge never goes online and only listens on your own PC. It starts off; nothing happens until you turn it on.
One editable source of truth, designed for round-tripping.
Your project is a single editable .focusforge.json; the HOI4 .txt/.yml/ideas/events are generated artifacts. That makes the tree easy to diff, version, and hand to an AI as structured data.
A searchable, categorized Help tab covers building, validating, exporting and the AI Bridge — the same content as this site’s documentation.
Free, for Windows. No account, no syntax to memorise.