"Getting set up: new project skeleton"

Empty or half-copied project won't Play, Razor can't find types, or you're unsure what the minimum viable folder layout is.

s&box projects are a small, opinionated tree: manifest, assets, code assembly referencing the Steam install, and a tiny startup scene that bootstraps the rest in code.

Folder layout

<project>/
├── <project>.sbproj
├── Assets/
│   ├── scenes/*.scene
│   ├── models/…
│   └── materials/…
├── Code/
│   ├── Assembly.cs
│   ├── <project>.csproj
│   └── <domain>/*.cs + UI/*.razor(.scss)
├── Editor/
├── ProjectSettings/
│   ├── Input.config
│   └── Collision.config / Platform.config
└── tools/                  # optional python generators

.sbproj essentials

{
  "Title": "YourGame",
  "Type": "game",
  "Org": "local",
  "Ident": "yourgame",
  "Schema": 1,
  "Metadata": {
    "MaxPlayers": 64,
    "MinPlayers": 1,
    "TickRate": 50,
    "GameNetworkType": "Multiplayer",
    "StartupScene": "scenes/main.scene"
  }
}

• TickRate: 50 → fixed update 50 Hz.
• Keep GameNetworkType: "Multiplayer" even for single-player (architecture stays open).
• StartupScene is what Play loads.

csproj / Assembly.cs

• TargetFramework net10.0, references Sandbox.*.dll under the Steam s&box bin/managed/ install.
• Verify without the editor:

dotnet build Code\<project>.csproj

global using Sandbox;
global using System;
global using System.Collections.Generic;
global using System.Linq;
global using System.Threading.Tasks;
global using YourGame; // must match @namespace in .razor files

Minimal scene + bootstrap

Scene JSON: exactly four GameObjects — Sun (DirectionalLight), Skybox (SkyBox2D + EnvmapProbe), Camera (CameraComponent, IsMainCamera: true), Bootstrap (custom component, plain __type class name, often namespace-free for scene binding).

protected override void OnStart()
{
    if (Scene.IsEditor) return;
    // 1. manager singletons (OnAwake publishes .Instance)
    // 2. static world
    // 3. player
    // 4. camera/sun attachments
    // 5. UI (one GO: ScreenPanel + PanelComponents)
    // 6. game-state last
}

Input.config

JSON list of { Name, GroupName, Title, KeyboardCode, GamepadCode }. WASD named Forward/Backward/Left/Right feeds Input.AnalogMove. Underscores must match; press/down/released names are case-insensitive.

Startup checklist

1. Folders + Title/Ident/StartupScene in .sbproj
2. Assembly.cs globals + razor namespace
3. 4-object scene + Bootstrap
4. dotnet build green
5. Optional: art generators (blender-headless-pipeline)
6. Prefix Log.Info with a project tag; watch console each Play

The editor only needs a mountable package + a startup scene. Bootstrap-in-code avoids scene/code drift and matches the lifecycle rules for singletons and UI. Headless dotnet build against the Steam assemblies is the fastest compile gate before you open the editor.