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Horizon
Minecraft: Java Edition 26.3, rewritten in Rust. Your worlds, the same rules and the same terrain as the Java game, checked against it by hundreds of differential tests, in one native program with no Java. Free, open source (MIT) and unofficial: you play it with your own copy of Java Edition.
What works today
Everything below is in the current release.
- The game. Survival, creative, hardcore and spectator; vanilla world generation in all three dimensions, mobs, villagers, raids, redstone, every command, the HUD and the recipe book. Vanilla saves open as they are, and worlds from 1.8 to 26.2 are upgraded.
- Multiplayer. Join vanilla and Horizon servers (online mode included), open a world to LAN, or invite friends with a code from the launcher's Home page.
- Graphics. Distant terrain up to 1,024 chunks, graphics presets, HDR and controllers, all off by default where they would change the vanilla look (settings).
- Packs. Resource packs, data packs and shader packs (below).
- Mods. Content mods and native Rust mods, installed from the launcher (below).
- Servers. Host one from the launcher, or run
horizon-serveron a VPS (below). - The launcher. It installs and updates the game, prepares its files from your copy of Minecraft, and updates itself.
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Nightly 2026-11-05 on a Mac mini (Apple M4 Pro, Metal): vanilla's textures, no mods or shader packs, render distance 32 with distant terrain on.
Download
Get the Horizon launcher from playhorizon.dev, or from the launcher releases:
| Platform | File | Needs |
|---|---|---|
| Windows x64 | horizon-launcher-setup.exe |
Windows 10 or 11, a GPU with Vulkan or DirectX 12 |
| Windows on Arm | horizon-launcher-setup-arm64.exe |
Windows 11 on Arm |
| macOS, Apple Silicon | horizon-launcher-macos-arm64.dmg |
macOS 12 or later |
| macOS, Intel | horizon-launcher-macos-x64.dmg |
macOS 12 or later |
| Linux x86-64 | horizon-launcher-linux-x86_64.AppImage or .tar.gz |
a glibc distribution, X11 or Wayland, a GPU with Vulkan or OpenGL 3.3 |
You also need a Microsoft account that owns Minecraft: Java Edition. You sign in with it in the launcher, which plays only with an account that owns the game (why). Horizon contains no Minecraft code or assets: an existing install (official launcher, Prism, MultiMC...) is reused, and without one the launcher downloads 26.3 from Mojang for your account. Step by step: Install and first launch.
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Mods and shader packs
- Content mods (
.hmod): blocks, items, recipes, loot, models and textures, with no code. - Native mods (
.hnmod): Rust that the launcher compiles into the game for you, with nothing to install. - Java mods (Fabric, NeoForge, Forge) don't run: Horizon has no Java. The launcher carries over the data and assets inside their jars, and imports modpacks (
.mrpack, CurseForge zips, Prism instances) the same way (modpacks). - Shader packs: Iris/OptiFine-format packs (
shaders/folders) and Horizon's own WGSL packs, under Video Settings → Shader Packs (pack format).
Mods are off by default: a fresh install plays exactly like vanilla 26.3. The launcher's Mods page browses Horizon's registry and Modrinth. Mods · make a mod.
Host a server
The launcher's Servers page creates, starts, backs up and updates a server, and invites friends. On a VPS, horizon-server installs with one command, needs no Java, and takes vanilla 26.3 and Horizon players alike. Host a server (reference).
Agent control
AI agents and scripts can play Horizon. horizon-ctl, shipped with the game, reads its state as JSON and acts like a player; horizon-ctl mcp serves the same commands over MCP.
horizon-ctl launch --world Survival --seed 5 --wait # finds the version the launcher installed
horizon-ctl state # position, health, food, target, screen...
horizon-ctl goto -0.5 65 -2.5 --near 2.5 # walks there along a path
horizon-ctl break -1 65 -3 # mines it; replies with the drops
horizon-ctl help lists every command. Agent control.
Build from source
Needs Rust 1.90+, Python 3.10+, JDK 25, and on Linux libasound2-dev libudev-dev. horizon-prepare builds the game's resources from your own copy of Java Edition 26.3 (checked against research-lock.json) and never downloads it:
- Client: play 26.3 once in the official launcher. Horizon reads
~/.minecraft(or--minecraft-dir/HORIZON_MINECRAFT_DIR). - Server jar: the 26.3 server jar (
downloads.server.urlinversions/26.3/26.3.json), passed once with--server-jarorHORIZON_SERVER_JAR.
git clone https://github.com/horizon-rust/horizon.git
cd horizon
cargo run --release -p horizon-prepare -- --prepare --server-jar ~/Downloads/server.jar # needs JDK 25
cargo run --release -p horizon-prepare -- sounds # optional: sounds from your launcher install
cargo run --release -p horizon-client
Prepared files land in the gitignored .local/: never commit or share them. Options, controls and architecture: the native client guide; all developer docs: docs/README.md.
Contributing
Issues and pull requests are welcome: read CONTRIBUTING.md (vanilla first, small pull requests), and see ROADMAP.md or playhorizon.dev/hub for what's next. Questions: Discord. Before a pull request, run the self-check and paste its output:
git config core.hooksPath .githooks
python3 tools/pr_ready.py
It runs rustfmt, clippy, the touched crates' tests, the Python tests, the public-tree check and the vanilla harnesses your change affects. Never commit game files, decompiled source or prepared resources.
Project status
Player-visible gaps: 0 open of the 833 the port ledger found, reading every vanilla 26.3 method against Horizon's code: vanilla behaviour a player would notice that Horizon doesn't have yet. By area: Animals 0; Monsters and bosses 0; Entities, projectiles, vehicles and decorations 0; Items, enchantments and inventories 0; Blocks, redstone and fluids 0; World, world generation and saves 0; Screens, HUD and client packets 0; Entity and block rendering, models 0; Server and players on the server 0; Mob AI, villagers and raids 0. This number goes down as gaps close (tools/parity_gaps.py); the harness results below say that what is tested matches.
The table is the project's own audit: every subsystem matches vanilla in every harness that compares it. 100% means 100% of what the harnesses compare, not that nothing else differs. What players still run into: known issues.
Java parity: 100%
Scores: 0 (absent), 0.25 (started), 0.5 (playable, major features missing), 0.75 (mostly complete) or 1 (complete and verified by differential tests); the percentage is their average. Last audited 2026-10-13: the harnesses pass on Linux and macOS. The port ledger adds a method-by-method view of what is ported.
| Subsystem | Score | Main gaps |
|---|---|---|
| Window, input and game loop | 1 | None: game loop, options, camera, auto-jump, toggle sprint/sneak and frame limiter match |
| Assets and resources | 1 | None: item models match over 196,290 stacks; the resource pack screen over 3,000 sessions |
| Network protocol and multiplayer | 1 | None: joins vanilla servers; the dedicated server matches vanilla's files, login, configuration, play and command tree; LAN discovery over 462 cases (offline mode only) |
| Chunk storage and palettes | 1 | None: client and saves share paletted containers, identical to vanilla over 266 scenarios |
| Section meshing | 1 | None: 112 scenes and over a million quads identical to vanilla |
| Rendering | 1 | None: entity models, block entity renderers (407 cases) and animations (296), HUD overlays (2,200 states), the recipe book (600), player list, subtitles and world border match |
| Lighting | 1 | None: saved and relit light matches vanilla, slabs and stairs included |
| World generation | 1 | None: 2,352 whole chunks over 225 structure sites, in all three dimensions, identical to vanilla |
| Region files and saves | 1 | None: saves round-trip with vanilla; worlds from 1.8 to 26.2 upgrade as vanilla's DataFixers do |
| Entities and physics | 1 | None: attributes, spawn rules, natural spawning (15,500 cases), raids and patrols (1,900), finalizeSpawn (24,000) and mob AI (92 scenarios) match |
| Interaction and inventory | 1 | None: menu clicks over 8,000 sequences; recipe book placement (6,000), buttons (1,200), saved book (1,500), loom and crafter screens (1,600) |
| Menus, HUD and chat | 1 | None: every command (758 over 39,685 inputs), scoreboards (81,000 operations), the player list (872,000 draw calls), chat and its suggestions (3,000 sessions) match |
| Audio | 1 | None: the sound engine, sound events, music, situational music, ambience and subtitles match vanilla |
| Block behaviours and ticking | 1 | None: block updates, random ticks, redstone, dispensers (6,000 cases), crafters (4,000), container spills (4,000), copper golems and the sculk family (435 scenarios) match |
Licence
MIT, for the project's original work; dependencies keep their own licences (notices). Horizon is made by Ludovic Marie (@ludovic111) and its contributors; support it on GitHub Sponsors.
NOT AN OFFICIAL MINECRAFT PRODUCT. NOT APPROVED BY OR ASSOCIATED WITH MOJANG OR MICROSOFT. Minecraft is a trademark of Mojang Synergies AB; its code and assets belong to Mojang and Microsoft under the Minecraft EULA.