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Make games without the bullshit.

From the creators of Garry's Mod — a game creation platform built on Source 2 and the latest C#. Create games with an intuitive editor, millisecond hot reloads, built-in multiplayer and share instantly.

Open source. No royalties. No catches.

steam github learn more

Latest News

Update 26.04.15

Developer Preview is closed 🛑, UI batching big FPS gains 🚀, tying up all the loose ends 🪢

3 days ago

Update 26.04.08

Sandbox open source 🎈, documentation open source 📃, games menu makeover 💅, Doo visual scripting 🪛 and the usual bug fixes

10 days ago

Update 26.04.01

New shadows are finally done, Sandbox got saves, we attended DreamHack and more!

17 days ago

Update 26.03.25

A future looking roadmap 🛣️, standalone games license 🪪, morphs + faceposer 🥸, and more!

24 days ago

Key Features

A few of our key features of the s&box engine.
Play

Play

Play hundreds of community-made games — from shooters 🔫 and platformers 🧗 to puzzlers 🧩 and racers 🏎️.

Team up with friends 👯‍♂️ right from the main menu and jump into any game — together.

No installs. No subs. No addons. Just click ⚡ and play 🎮.

Create

Create

Create your own games 🛠️ and playtest instantly with our familiar scene system 🎬.

Build with our first-rate C# API — easy for beginners, powerful for pros 💪.

/// <summary>
/// Moves the object forward in the camera direction when pressing forward
/// </summary>
public class ShipControls : Component
{
    /// <summary>
    /// The speed to move the object
    /// </summary>
	[Property, Range( 0, 1000 )] 
    public float Speed { get; set; } = 200.0f;

	protected override void OnUpdate()
	{
		if ( Input.Down( "forward" ) )
		{
			var forward = Scene.Camera.WorldRotation.Forward;
			WorldPosition += forward * Speed * Time.Delta;
		}
	}
}
C#

C#

Write in modern C# 14 with the latest language features — no legacy baggage 🧳.

Powered by .NET 10 and a familiar Component System — intuitive, flexible, and fast ⚡.

Enjoy smooth performance with no GC stutters 💨.

Open Source

Open Source

Our code is on GitHub 🤓 and is MIT licensed 😍 - so you can do whatever you want with it.

We believe that the positives of open source massively outweigh any negatives 🧙🏼.

Share

Share

Sharing your game is effortless — just click to publish 📤. Everything uploads automatically and is ready to play instantly 🚀.

Play Fund

Play Fund

Earn real money 💰 when people play your games — our Play Fund rewards creators based on engagement, not ads or microtransactions.

The Play Fund grows with our success - so the more players the game gets, the bigger the pool will be. So far we've paid $465,631.81 !

Multiplayer

Multiplayer

Multiplayer is built right into the engine 🔧 — no setup needed.

Playtest your games or levels instantly with the community 🧪🌍.

Hotload

Hotload

See code changes take effect instantly with blazing-fast hotloading ⚡ — no compiling, no restarts.

Cloud Assets

Cloud Assets

Create your games and levels with a huge library of assets 🧱.

No downloads, no subs — just drag straight from the asset browser into your scene 🎯.

Hammer

Hammer

Create levels with Valve’s powerful Hammer Editor 🔨.

We’ve made it moddable — add new tools, UI, primitives, and more 🔧.

Action Graph

Action Graph

Use our visual scripter, ActionGraph, to build interactive experiences — no code, no messy chains of entities 🧩⚡.

Shader Graph

Shader Graph

Create unique materials and post-processing effects 🎨⚙️ with ease using our Shader Graph.

Virtual Reality

Virtual Reality

We’re committed to making VR on PC easy to develop and seamless to play 🥽🚀.

Publishing

Publishing

Coming soon: export and release your s&box games as standalone titles on Steam 🚀.

Completely free, no royalties, no strings. Your game, your name, your revenue 💼.