Download MJOLNIR Launcher

Your way into Campaign Evolved multiplayer. Install all 19 classic Halo CE maps, multiplayer mods, and creator tools from one launcher.

Windows Installer (.exe)

Requires Windows 10/11 (64-bit) and WebView2 runtime

Download the installerorLauncher releases on GitHub

Installed? Bring your friends.

Set up Campaign Evolved multiplayer

  1. 01

    Get the launcher

    Install MJOLNIR on Windows and set up mods from My Mods. You need your own installed copy of Halo Campaign Evolved.

  2. 02

    Install multiplayer

    Open the launcher's Multiplayer page and select Install multiplayer. It installs the classic maps, shared content, and required mods.

  3. 03

    Bring your fireteam

    Launch the game, open MULTIPLAYER, choose a map and mode, invite your friends, and start the game. Everyone needs the same maps installed.

Multiplayer is in alpha with up to 16 players. Works on Steam and Game Pass, and the two can play together. Each player needs their own copy of the game and the same maps.

Multiplayer setup & FAQs

Verify Your Download

Always verify the SHA-256 checksum to ensure your download hasn't been tampered with.

1

Official Build Checksums (Latest Release)

Fetching latest build checksums from CDN...
2

Compute the hash of your downloaded file

PowerShell (Windows)
(Get-FileHash .\MJOLNIR-Launcher*-setup.exe -Algorithm SHA256).Hash
Command Prompt
certutil -hashfile MJOLNIR-Launcher-latest-setup.exe SHA256
3

Compare the hashes

If the hash you computed exactly matches the one in checksums.txt, your download is authentic and unmodified.

The tools install from here too

The launcher's Tools view installs and updates the MJOLNIR Tag Editor — the Guerilla-style editor for the game's tags, textures, audio and scripts — and checks every build against its published hash.

See the tools

Prefer a command line?

mjolnir reads and edits the same tag data from a terminal — list a group, print a tag's decoded fields, change one, and bake the result into a container the game loads. It runs on Windows, Linux and macOS, with a checksum published for every build.

# Windows
scoop bucket add mjolnir https://github.com/devnull9090/mjolnir-core
scoop install mjolnir

# macOS and Linux
brew tap devnull9090/core https://github.com/devnull9090/mjolnir-core
brew install mjolnir

Also as .deb and .rpm, or a plain archive. The Linux build is statically linked, so it runs on any distribution.

Download an archiveRead the walkthrough

System Requirements

OSWindows 10/11 (64-bit)
RuntimeWebView2 (included in Win 11)
GameHalo Campaign Evolved (Steam or Game Pass)
Disk~50 MB for launcher