Technical documentation

Getting Started: Your First Tag Edit

This walks the whole path, from a clean install to a value you changed showing up on the HUD. It

Making Your First Mod

mjolnircore.com account (Discord sign-in) if you want to publish

Getting Started: Editing Halo Campaign Evolved Tags

A practical guide to reading and changing Blam tags, with the mjolnir command line

Swapping a Texture

mjolnir command line

Making a custom level

The MJOLNIR level pipeline is this game's answer to the old Halo Editing Kit:

Driving the Game From Outside

2026.06.26.1097863.1-Rel-i343-Meteorite-2606-CU2 (Steam).

Build Lock

Every finding in docs/ is only true of the build it was measured on, and the game updates without

Game Update Pipeline

Steam updates the game in place. The moment a patch lands, the previous build is gone, and with

Blam Tag Data in Halo Campaign Evolved

Does Halo Campaign Evolved run on real Blam tag data like the classic games, or are bipeds,

Blam Tag Body Format (`blay` Layout Section)

Verified: the Blam tag body that follows the 0x4C-byte container header is

Getting an Edited Tag Into the Game

with the P patch suffix mounts, wins the chunk lookup, and its Blam payload is what the

Cooked Texture2D / Virtual Texture Format in Halo Campaign Evolved

A shipped Texture2D in this build cooks one of two ways, and both are common:

Where the Audio Lives in Halo Campaign Evolved

Almost none of the game's audio is reachable through the IoStore reader. The

HaloSimulation_tag_release.dll Analysis

| Property | Value |

The Blam console

Halo Campaign Evolved's simulation DLL still carries the classic Blam

MJOLNIR Multiplayer Investigation — Session Notes

| What | Path |

The `.mjolnir` Release Archive

A .mjolnir file is a plain zip with a manifest at the root and IoStore

MJOLNIR Hub — Mod Distribution Architecture

deviations each phase note records. Phase 4 has not started. Section headings note what is live.

Mod Authoring: Design

distribution are future phases.

The MJOLNIR level format (`.level.json`)

The interchange format of the level authoring pipeline: what the Blender exporter writes, what

Mod Signing and Attribution: Design

0005 carries the key registry and per-release attribution. Rollout step 2

Contributing a Code Mod

mods — tags, textures, maps, sounds — you don't need any of this: upload a

Security advisory: the `arrayref` 0.3.10 supply-chain attack

On 2026-08-20 a malicious version of the widely used Rust crate arrayref