Achievement Manager

A Millennium plugin that adds an Achievement Manager tab to a game's achievements window in the Steam library — next to My Achievements and Global Achievements (and Achievement Groups, if you use that plugin).

The tab is built only from Steam's own controls — rows, toggles, dropdowns, button rows, search box, progress bar. There are no custom windows or pop-ups.

• every achievement of the game as a row: icon, name, description, unlock date, toggle
• search, filter (All / Unlocked / Locked / Changed) and sort
• Unlock shown / Lock shown for whatever the search and filter currently show
• changes are staged first; Apply asks for a second click, then writes them to your Steam account and waits for Steam to confirm the save

Install

Grab achievement-manager.star from the Releases page, or build it from this source (see Building below).

1. Copy achievement-manager.star into <Steam>\millennium\plugins\.
2. Open Millennium → Plugins, enable Achievement Manager, restart if asked.
3. Open a game's page → the achievements button → the new tab.

Notes

• Windows only. The helper and the process code are Windows-specific.
• Command-line length is not a limit: long lists go to the helper through a temporary file.
• If the other tabs still show the old state after Apply, close and reopen the achievements window.
• Achievement names are in Steam's current language when the schema has it, English otherwise.

Building

The plugin is a Starlight project (millennium.toml).

Requirements: Millennium >= v3.5.0 and Bun >= v1.4.3.

git clone https://github.com/madmaxgrey/AchievementManager
cd AchievementManager
bun install
bun run build     # packs achievement-manager.star and installs it into Millennium

bun run dev watches the source and reloads the plugin while you work.

Files

millennium.toml                      manifest (plugin id, backend, frontend, resources)
backend/main.lua                     load / unload hooks
backend/rpc_functions.lua            am_status / am_apply, helper build + launch
resources/steam_achievement_helper.cs   the Steam client helper (bundled, compiled on first use)
frontend/index.tsx                   tab injection, UI and Steam stats schema reader

License

MIT — see LICENSE. Maintained by madmaxgrey.

Acknowledgements

The helper follows the approach of gibbed/SteamAchievementManager (Steam's stats schema file).