horizon

horizon-rust

4.4k stars401 forksRustMIT

differential-testinggame-enginegamedevlinuxminecraftminecraft-javareimplementationrustvoxelvulkan

A Rust-native Minecraft Java Edition 26.3 reimplementation that plays your existing worlds with vanilla-compatible behavior.

Horizon rebuilds Minecraft Java Edition 26.3 in Rust while checking behavior against vanilla with 281 differential harnesses. Sign in through its launcher, prepare files from your owned copy, then play singleplayer worlds, multiplayer, or modded profiles. It is unofficial and contains no Minecraft code, assets, or data.

For Minecraft owners with supported GPUs wanting a native Rust client, and automation authors controlling game sessions

Desktop appv0.2.97Needs a Minecraft-owning Microsoft account

Use cases

Play existing Minecraft worlds with vanilla-format saves
Host a multiplayer world through LAN, servers, or Tailscale
Customize gameplay with content mods adding blocks, items, data, assets
Import compatible modpacks from Modrinth or CurseForge
Explore terrain farther away up to 1024 chunks

Key features

Vanilla behavior validation: 281 Linux differential harnesses pass
Vanilla save compatibility: Reads saves and upgrades worlds from 1.8 to 26.2
Multiplayer options: Friend codes, LAN, and online-mode servers
Dedicated server management: Launcher creates, backs up, updates servers; Tailscale invites
Native and content mods: Java mod jars do not run
Agent command interface: CLI JSON output and MCP screenshots

Under the hood

4 parts

Horizon treats Minecraft Java Edition 26.3 as the behavioral specification, porting its behavior into Rust and checking it with differential probes and harnesses. The playable client coordinates a 20-tick simulation, streamed world work, interaction, inventory, and HUD rendering.

AGENTS.md; README.md (Java parity: 100%); crates/horizon-client/src/game.rs (module documentation); crates/horizon-world/examples/probe/main.rs (module documentation)

Playable client
Runs simulation, world streaming, interaction, inventory, and HUD.
crates/horizon-client/src/game.rs
World engine
Implements world generation, storage, and parity probes.
crates/horizon-world/
Renderer
Renders the native game client with GPU graphics.
crates/horizon-client-render/
Launcher
Installs, updates, prepares, and launches Horizon instances.
launcher/src/

Built with

Rustwgpu 30.0.1winit 0.30.13GPUI 0.2.2VulkanClap 4Serde 1Python 3.10+ for harness tools

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