A modular foundation for s&box

Build modular games with Lithium.

A developer framework for creating extensible systems, services and addons in s&box.

Open source · C# native · Built for s&box

using Lithium.Addons;

namespace Lithium.House;

[Addon("thepanicdept.lithium_house", "Lithium House")]
public sealed class HouseAddon : Addon
{
    protected override void OnAddonLoaded()
    {
        Log.Info("House Addon Loaded");
    }

    protected override void OnAddonUnloaded()
    {
        Log.Info("House Addon Unloaded");
    }
}

Sandbox.Addons● Lifecycle ready

Runtime

House Addon Loaded

01C# native

02Built for s&box

03Modular addons

04Component services

Core systems

Systems that stay composable.

Lithium keeps package identity, runtime ownership and dependency contracts visible, so features can grow without turning into one monolithic game project.

01 / Package

Addon packages

Keep gameplay features independent, discoverable and tied to an explicit package identity.

02 / Runtime

Component services

Model reusable systems as s&box components and let Lithium manage their runtime lifecycle.

03 / Contract

Dependency manifests

Describe package identity, load priority and required or optional dependencies in one place.

Experimental

04 / Signals

Event-driven APIs

Connect systems through named events and callable boundaries without hard-wiring every module.

Architecture / 01

Built around the way s&box works.

Lithium adds a small coordination layer around familiar components and packages. Each layer has one job, and every boundary stays explicit.

Game

Your experience

Lithium Runtime

Discovery & lifecycle

Addons

Feature packages

Services

Scene-owned systems

Features

Gameplay modules

Discover

Resolve packages and their concrete addon contracts.

Mount

Attach reusable services to the active scene lifecycle.

Compose

Build gameplay features without collapsing module boundaries.

Developer experience / 02

Small APIs. Clear ownership.

Lithium builds on C# and familiar s&box primitives. The result is code that says what it owns, when it starts and what it depends on.

Current API surface

HouseAddon.cs

A smaller surface for a clearer system.

Own setup and teardown in a small lifecycle that stays close to the feature.

namespace
Sandbox.Addon

HouseAddon.cs

using Lithium.Addons;

namespace Lithium.House;

[Addon("thepanicdept.lithium_house", "Lithium House")]
public sealed class HouseAddon : Addon
{
    protected override void OnAddonLoaded()
    {
        Log.Info("House Addon Loaded");
    }

    protected override void OnAddonUnloaded()
    {
        Log.Info("House Addon Unloaded");
    }
}