@babylonjsmarket/ecs ships as a single ESM-only npm package. The core has zero runtime dependencies — renderer adapters and physics engines are optional peer dependencies that you install only when you need them.

The core package

npm install @babylonjsmarket/ecs

That's enough to start writing Components, Entities, Systems, and a World. You can run the full ECS in vitest without touching a browser — useful for unit-testing game logic.

Picking a renderer

The framework defines the RendererAdapter interface. Two concrete adapters ship inside @babylonjsmarket/ecs, behind subpath imports. Install the underlying engine only for the one you actually use.

BabylonJS (recommended)

First-class scene support and built-in Havok physics.

npm install @babylonjs/core @babylonjs/loaders @babylonjs/havok

import { BabylonAdapter } from '@babylonjsmarket/ecs/babylon';

Three.js

Leaner runtime. No bundled physics — bring your own integrator via the physicsFactory constructor option.

npm install three

import { ThreeAdapter } from '@babylonjsmarket/ecs/three';

MockRendererAdapter (tests)

No install. Lives in the core entry. Used in vitest to assert that systems made the right renderer calls without a browser:

import { MockRendererAdapter } from '@babylonjsmarket/ecs';

Module resolution

The package is ESM only. Your project's package.json should include "type": "module" or your bundler must support ESM imports.

The subpath exports use modern conditional exports:

@babylonjsmarket/ecs              → core + Mock + race tracking
@babylonjsmarket/ecs/babylon      → BabylonAdapter
@babylonjsmarket/ecs/three        → ThreeAdapter
@babylonjsmarket/ecs/renderer-types → RendererAdapter interface + Vec3/Color tuples
@babylonjsmarket/ecs/testing      → runMechanicContract helper

Every modern bundler — Vite, esbuild, Rollup, webpack 5+ — resolves these correctly. If you're stuck on an older toolchain that doesn't honor exports, upgrade.

TypeScript

The package ships full .d.ts declarations. No separate @types/... package needed. The RendererAdapter interface is fully typed; opaque handles like MeshHandle use phantom types to keep handles from one adapter from leaking into another.

What's next

The Quick Start walks through wiring all this together — adapter, World, a couple of Systems, a moving capsule on screen.