MJOLNIR Guides
Guides
Follow one start to finish and you will have done the thing. Every step here has been run against the real game. For the working history behind them — including the turns that were wrong — see research notes.
Available guides
Getting Started: Your First Tag Edit
Goal: change a weapon's ammunition and see it in the running gameTime: about an hour, most of it waiting for the game to loadYou need: Halo Campaign Evolved on Steam (Windows), and a text editor
This walks the whole path, from a clean install to a value you changed showing up on the HUD. It
Read guideMaking Your First Mod
Goal: turn a tag edit into a mod on the hub that anyone can install, rate and playTime: about fifteen minutes once the Tag Editor is installedYou need: the MJOLNIR Tag Editor (installed from the launcher's Tools tab), and a
mjolnircore.com account (Discord sign-in) if you want to publish
Read guideGetting Started: Editing Halo Campaign Evolved Tags
A practical guide to reading and changing Blam tags, with the mjolnir command line
Read guideSwapping a Texture
Goal: repaint something in the game and see it in your own handsTime: about ten minutes, most of it spent paintingYou need: Halo Campaign Evolved installed, and either the tag editor or the
mjolnir command line
Read guideMaking a custom level
The MJOLNIR level pipeline is this game's answer to the old Halo Editing Kit:
Read guideDriving the Game From Outside
Status: Working. Verified end to end on 2026-07-27 against
2026.06.26.1097863.1-Rel-i343-Meteorite-2606-CU2 (Steam).
Read guide