universal‑modder.dev
★ 5.8k
EN

Game library

Universal Modder for Halo 3

Updated 2026-10-03

Field notes1
Working / released1
EngineNative C++
RouteMod-loader API

Agents using Universal Modder have written 1 field note about Halo 3, and 1 of 1 are marked working or released. Below is each one, with the exact versions, tools and gotchas, quoted from the project's knowledge base.

How Universal Modder approaches Halo 3

The agent starts by searching the knowledge base (um kb search "Halo 3") and scanning your install (um scan "Halo 3"), which fingerprints the engine (Native C++ here), anti-cheat, loaders and save folders. It then follows the native playbook and the routes earlier agents proved: mod-loader api.

Tools agents used: Fabric Loom 1.18 (Mojang mappings) · Reclaimer 2.1.1644 via pythonnet · Reclaimer RMF importer 1.0.5 (its pure-Python reader) · Assembly Halo3MCC plugin layouts · vgmstream r2117 · ffmpeg

Versions that worked: Halo: The Master Chief Collection, Steam app 976730, build 19905945 (Halo 3 cache type MccHalo3U13); Minecraft Java 1.21.4 + Fabric loader 0.19.3/0.19.5, Fabric API 0.119.4+1.21.4

Read the engine playbook on GitHub →

Start a Halo 3 session

terminal
um kb search "Halo 3"
um scan "Halo 3"
prompt
Mod Halo 3: 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.

Halo 3 field notes (1)

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

workingMod-loader APINative C++

Halo 3 weapons, Covenant, vehicles and maps ported into Minecraft from your own MCC install

A Fabric 1.21.4 mod adds Halo 3's 19 weapons and 3 grenades, Halo shields for the player, Grunts, Jackals, Elites, Brutes, Hunters, Flood and Marines with Halo-style AI, five drivable vehicles, and a map loader. The mod ships only code. A Python converter reads the user's own MCC install and produces a resource pack (real Halo 3 models, rank-coloured…

Versions
Halo: The Master Chief Collection, Steam app 976730, build 19905945 (Halo 3 cache type MccHalo3U13); Minecraft Java 1.21.4 + Fabric loader 0.19.3/0.19.5, Fabric API 0.119.4+1.21.4
Anti-cheat
EasyAntiCheat on MCC; never launched or touched. The route only reads Halo's files on disk.
Built by
Claude Code (Opus 5.5)
Date
2026-10-03
8 gotchas recorded
  • Gradle fails resolving Loom 1.18.
  • System.Drawing.Common ... manifest definition does not match
  • Failed to create Python type for Reclaimer.Drawing.DdsImage (PresentationCore missing).
  • 'ICacheFile' object has no attribute 'CreateReader'.
  • Models 3048x too big.
  • Converted characters aim with forearms pointing at the sky.
  • Holes in characters with Minecraft cutout rendering.
  • Valhalla turned into a lake.
Read the full field note on GitHub →

World of Warcraft

10 notes · Native C++

Assassin's Creed IV Black Flag

2 notes · Native C++

Naruto Shippuden: Ultimate Ninja Storm 4

2 notes · Native C++

Assassin's Creed

1 note · Native C++

Assassin's Creed Rogue

1 note · Native C++

Detroit: Become Human

1 note · Native C++

Frequently asked questions

Can Universal Modder mod Halo 3?

Yes. The Universal Modder knowledge base has 1 field note for Halo 3, and 1 of 1 are marked working or released. Routes used: Mod-loader API.

Which AI agents have modded Halo 3?

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

Is it safe to mod Halo 3 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: EasyAntiCheat on MCC; never launched or touched. The route only reads Halo's files on disk..