An open-source Age of Empires-inspired RTS built with Unity 6 and a Rust relay server backend, featuring deterministic lockstep multiplayer.

Play the Demo

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Features

Gather resources on a procedurally generated map

Build a civilization based on the English, French, or Holy Roman Empire

Age of Empires-inspired medieval combat system

Support for multiplayer 1v1, 2v2, 3v3, and 4v4!

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Tech Stack

• Engine: Unity 6 (6000.3.9f1) with URP and New Input System
• Backend: Rust (Axum + Tokio + WebSockets), PostgreSQL for matchmaking
• Multiplayer: Deterministic lockstep with dynamic input delay
• Math: Fixed-point (Q16.16) arithmetic for cross-platform determinism

Getting Started

Unity Client

1. Clone the repository
2. Open the Open Empires/ folder in Unity Hub (not the repo root)
3. Use Unity 6 (6000.3.9f1) or compatible
4. Open the main scene and press Play

Backend Server

1. Install Rust
2. Install PostgreSQL and create a database
3. Set the DATABASE_URL environment variable (e.g. postgres://user:pass@localhost/openempires)
4. Run the server:

   cd backend
   cargo run

5. Optional: Place a MaxMind GeoLite2 City database at data/GeoLite2-City.mmdb for player geolocation

WebGL Build

A pre-built WebGL version is available in the docs/ folder and can be served as a static site.

Architecture

Sim/Render Separation

All gameplay state lives in pure C# simulation classes (GameSimulation, SquadData, SoldierData, MapData) with no Unity dependencies. MonoBehaviour renderers (SquadView, SoldierView, MapRenderer) read simulation state and update visuals each frame.

Deterministic Lockstep

Players send commands to a relay server, which broadcasts all inputs. Clients execute the same commands in the same order using fixed-point math and a deterministic PRNG, with checksums to detect desync.

Unit System

Individual units are controlled directly. Villagers gather resources and construct buildings, while military units (spearmen, archers, horsemen, etc.) handle combat.

Resource Gathering

Villagers gather resources (food, wood, gold, stone) to fuel your economy and advance through ages.

Project Structure

Open Empires/
  Assets/
    Scripts/
      Core/           # GameSimulation, GameBootstrapper, GameSetup
      Units/           # UnitData, movement, combat
      Network/         # CommandSerializer, relay client
    Prefabs/           # Unit and building prefabs
    Scenes/            # Game scenes
backend/               # Rust relay/matchmaking server
docs/                  # WebGL build

Community

• Discord - Join the community, ask questions, share feedback
• YouTube - Devlogs and gameplay videos

Contributing

See CONTRIBUTING.md for guidelines on how to contribute.

License

This project is licensed under the MIT License. See LICENSE for details.

For third-party license information, see THIRD_PARTY_NOTICES.md.