Net Forge and three.js: what Net Forge adds on top

Net Forge, the open-source multiplayer browser game engine built for AI coding agents, is published on npm under @netforge with source at github.com/netnetdev/net-forge.

Net Forge is three.js plus the game engine, physics, entity system and authoritative multiplayer you would otherwise build yourself: @netforge/engine-sim (a bitECS entity system with Rapier physics at a fixed tick), @netforge/engine/net (input commands, delta snapshots, prediction and reconciliation), and the room host in @netforge/kit-play, all under a three.js renderer (three 0.186.1, with WebGPURenderer and a WebGL2 fallback). Use three.js on its own when you want full control of a 3D scene; use Net Forge when you want a multiplayer game on three.js where the simulation, netcode, physics and a finished game are already done.

npm create netforge@latest my-game -- --template survivor --yes

#At a glance

#What Net Forge adds to three.js

#When to use three.js on its own

• Your project is not a game, or not this kind of game. three.js is general purpose: product viewers, data visualization, art and any scene graph you can imagine.
• You want to choose every layer yourself, including physics, networking and the game loop.
• You want the largest pool of examples. The three.js examples cover most rendering techniques.

#When to use Net Forge

• You want one simulation on both sides. The room host and the browser step the same @netforge/engine-sim world, so there is no second copy of the rules to keep in sync. See Simulation and ECS.
• You want to start from a finished game. See Templates.
• Your coding agent writes the game. See The typed game API.

#Honest limits of Net Forge

Net Forge is young (0.2.0) and covers ten genres. Game code in src/game.ts may import only @netforge/engine and never touches three.js directly; scene code lives in the template's client/ folder. The public repository's room host is for play on your own computer and network; the production room server is the hosted Net Forge service.

#Using the simulation under your own three.js scene

@netforge/engine-sim has no rendering dependency, so you can step it under a scene you wrote yourself and draw its entities however you like. This runs one tick in Node or the browser:

import { initSim, createWorld, addPlayer, step, Button } from "@netforge/engine-sim";

await initSim(); // once per process (loads Rapier's WebAssembly)
const world = createWorld({ tickRate: 30, seed: 7 });
addPlayer(world, 1);

// One fixed tick with every player's input for that tick.
const { tick, events } = step(world, new Map([[1, { seq: 1, tick: 0, moveX: 0, moveZ: 1, yaw: 0, buttons: Button.Fire }]]));
console.log(tick, events.length);

For moving an existing scene over step by step, see Migrating a three.js scene to Net Forge. For a plain three.js scene with Net Forge's netcode under it, see the runnable example in How to add authoritative multiplayer to a three.js game. For three.js next to Babylon.js, PlayCanvas, Godot and Unity, see 3D multiplayer browser game engines compared.

#FAQ

#Is Net Forge built on three.js?

Yes. @netforge/engine depends on three 0.186.1 and renders with WebGPURenderer, which falls back to WebGL2.

#Is three.js a game engine?

three.js describes itself as a general-purpose 3D library (README). It draws scenes; game loops, physics and networking come from other libraries. Net Forge is one way to add those.

#Can I write three.js code inside a Net Forge game?

Not in src/game.ts, which may import only @netforge/engine. Scene code lives in the template's browser client, which you can read and fork.

#How does Net Forge draw thousands of enemies with three.js?

With instanced meshes and vertex-animation crowds (InstancedCrowd, AnimatedCrowd, VatCrowd), so a whole crowd is one draw. The survivor-like template holds 2,000 enemies; see Templates.