horizon-airdef/website/docs/install.md

# Install and first launch

Download the launcher, let it install Horizon, then prepare the game from your own copy of Minecraft. It takes a few minutes, and you do the preparation once.

## What you need

- **Minecraft: Java Edition 26.3, played once.** Install it with the official Minecraft launcher (or Prism Launcher, MultiMC, the Modrinth App, ATLauncher or GDLauncher) and start 26.3 once, so it downloads its files. Horizon reads them from there and never copies them anywhere else.
- **Java 25, a JDK**, for the one-time preparation only (the game itself needs no Java). Nothing to install: the launcher uses the Java the Minecraft launcher downloaded for 26.3, or downloads that same Java from Mojang. A JDK you installed yourself (for example [Eclipse Temurin 25](https://adoptium.net/temurin/releases/?version=25)) works too.
- **A computer on the [supported list](/docs/#supported-systems).** On Linux and Windows that means a graphics card with Vulkan (or DirectX 12 on Windows).

## Download the launcher

Get the newest launcher from the [Download button on the home page](/), which picks the right file for your system, or from [the launcher releases on GitHub](https://github.com/ludovic111/horizon/releases?q=launcher-v&expanded=true).

- **Linux:** download `horizon-launcher-linux-x86_64.tar.gz`, extract it and run `horizon-launcher`.
- **macOS:** download `horizon-launcher-macos-arm64.dmg`, open it and drag Horizon onto Applications. The first time, macOS says it cannot check the app, because it is not signed with a paid Apple developer account. On macOS 14 and earlier, right-click Horizon, choose **Open**, then **Open** again. On macOS 15 and later, open it once, then go to **System Settings, Privacy & Security** and choose **Open Anyway**. After that it opens normally.
- **Windows:** download `horizon-launcher-windows-x64.zip`, extract it and run `horizon-launcher.exe`.

Every release also carries `SHA256SUMS` and a signature, `SHA256SUMS.sig`, if you want to check your download. The launcher does not check that signature for you yet.

## First launch

1. Open the launcher. On the **Play** page, if it says "No version installed yet", choose **Choose a version**. On the **Versions** page, install the newest one. The launcher installs it in its own folder.
2. Back on **Play**, the launcher says "Not prepared. Horizon needs the files of your own Minecraft 26.3." Choose **Prepare**. It finds your Minecraft folder by itself in the usual places. If it cannot, it lists where it looked, and **Choose…** next to the Minecraft folder lets you point it at yours.
3. Wait a few minutes. When it says "Prepared for Minecraft 26.3", choose **Play**.

The game opens on vanilla's title screen. Your worlds, options and logs live in the game folder, which is not inside a version's folder, so updating or removing a version never touches them:

- Linux: `~/.local/share/horizon`
- macOS: `~/Library/Application Support/horizon`
- Windows: `%APPDATA%\horizon`

> **No Microsoft sign-in yet.** The launcher's Settings page has an Accounts section, but signing in with a Microsoft account does not work for players today. It needs an app registration and an approval from Mojang that the project does not have yet. You do not need an account to play single player.

## Updating

- **Horizon.** The launcher looks for a new release when it starts and every four hours while it is open. With **Install new versions automatically** on (the default), it installs one and moves you to it if you were on the newest. New releases come out many times a day, and old versions stay installed until you remove them on the **Versions** page.
- **The launcher.** It updates itself from its own releases, then shows **Restart** in its footer. A launcher from before 0.2 (0.16 or older) updates twice in a row: first to 0.17, then to 0.2. Then it installs Horizon 0.2 like any update.

## Stable and Alpha

> **Next launcher release.** The Updates switch below is merged but not in a launcher release yet. Launcher 0.17 has a **Beta builds** switch in Settings instead, which installs every new build at once, as Alpha does.

In **Settings**, **Updates** picks which builds install by themselves:

- **Stable** (the default): a tested build about once a day.
- **Alpha**: every change as soon as it is built, several times a day. It can break. A launcher left open looks for new builds every 30 minutes, instead of every four hours.

Every new release is an Alpha build first. Once a day (20:00 UTC, 21:00 in Paris in winter), the newest one that has been out for six hours, passed its smoke test and has no known blocker becomes Stable. Alpha builds come out many times a day, and Horizon as a whole is still in beta; Stable is the tested ones. The **Versions** page shows each version's channel, and you can install any of them by hand.

## The Versions page

It lists Horizon's releases, newest first. You can install a version, remove it, or choose which one **Play** starts. Each release's notes are on the **Patch notes** page, and on [GitHub](https://github.com/ludovic111/horizon/releases).

## Something went wrong

See [Logs, crashes and bug reports](/docs/troubleshooting).