⭐ Built for BetterSteamTools. BST is the actively maintained continuation of OpenSteamTool — use it instead of OST. It reads luas from
config\stplug-in(OST usedconfig\lua), so OSTLua installs there by default.Already have luas in the old folder? Open any store page after updating and OSTLua will offer to move them for you — one click, nothing moves without your OK, and any file that already exists at the destination is left untouched.
⚠️ Millennium 3.4.0+ users: you need v1.3.0 or newer. Millennium 3.4.0 changed how plugin scripts are injected and older OSTLua builds show no UI at all on it.
- One-click install
- Quick Install — installs the lua and loads the game's builds in one go
- Downgrade by build — pins every depot together, not just one
- Multiple download sources
- Automatic migration from the old OpenSteamTool lua folder
- Millennium installed on Steam (3.4.x supported).
- BetterSteamTools installed. (Legacy OpenSteamTool still works — see below.)
- Install Millennium and BetterSteamTools (see their READMEs).
- Copy the
OSTLuafolder into your Millennium plugins directory:Steam\Millennium\plugins\OSTLua\ - Enable OSTLua in Millennium's plugin manager.
- Restart Steam.
No config files to set up — the plugin creates everything on first run. Open the OSTLua button on any store page to add your Hubcap API key (optional; the free sources need no key).
OSTLua writes to config\stplug-in by default (BST). If you're still running plain OST, set the folder back by editing backend\config.json:
{ "lua_dir_name": "lua" }OSTLua always reads from both locations, so downgrading keeps working either way.
Open a game's Steam store page and click the OSTLua button (top-right).
- Load builds from SteamDB — reads the game's build list once (
13 Mar 2026 — build 22277314, …). - Pick a build → Apply. OSTLua opens that build's SteamDB page, reads every depot's manifest from it, and pins them together.
- Revert clears every pin and puts the game back on the latest build.
The card shows what's pinned, e.g. current: 9166256367562763038 · build 22277314 · 13 Mar 2026.
A game's files are split across several depots. Pinning only the "main" one leaves the rest on the newest build, and you end up with a half-old, half-new install that looks like "I picked an old version and it downloaded the latest anyway".
Applying a build fixes that: OSTLua takes the depot manifests off that build's SteamDB page and pins them as a set. Depots the build didn't touch are pinned at the manifest they already had — so nothing silently floats to latest. Depots your lua doesn't contain (blacklisted ones) are ignored.
If the build page can't be read properly, nothing is written — it tells you to try again rather than leaving a mixed install behind.
🔑 Sign in to SteamDB through Steam. Logged-out visitors only see a short slice of history. Signed in, you get the game's full build list.
Restart Steam, then use Properties → Installed Files → Verify integrity of game files. Steam sometimes relabels the manifest without actually fetching the older files; verifying forces it to reconcile against the pins.
Note that Steam's Build ID in the game's Updates tab still shows the latest build — it records the public branch's id no matter which depot manifests are mounted. The depot manifests are the real state.
⚠️ Installed games before? Re-download their lua. Older builds installed games with the manifest pinned, which could silently block Steam updates. If a game isn't updating, re-download its lua through OSTLua (or hit Revert) — that clears the pin so it updates normally again.
This project is provided for research and educational purposes only. You are responsible for complying with local laws, platform terms of service, and software licenses.