Build settings and scene order in Unity - Deep Dive

Overview - Build settings and scene order

What is it?

Build settings in Unity are where you prepare your game or app to be made into a final product. Scene order is the list of scenes that Unity will include and the order it will load them when the game starts. Together, they control what parts of your project are included in the final build and how the game flows from one scene to another. This helps you organize your game’s levels, menus, and other screens.

Why it matters

Without build settings and scene order, your game might miss important parts or load scenes in the wrong order, causing confusion or crashes. They solve the problem of managing many scenes and deciding which ones players see first. This makes your game feel smooth and professional, and ensures it works correctly on different devices.

Where it fits

Before learning build settings and scene order, you should understand what scenes are and how to create them in Unity. After mastering this topic, you can learn about scripting scene loading, managing game states, and optimizing builds for performance.

Mental Model

Core Idea

Build settings and scene order tell Unity which scenes to include and in what order to load them when making your game.

Think of it like...

It's like packing a suitcase for a trip: build settings decide what clothes (scenes) go in the suitcase, and scene order decides the order you wear them during your trip.

┌─────────────────────────────┐
│       Build Settings        │
│ ┌─────────────────────────┐ │
│ │ Scene List (Included)   │ │
│ │ 1. MainMenu             │ │
│ │ 2. Level1               │ │
│ │ 3. Level2               │ │
│ │ 4. GameOver             │ │
│ └─────────────────────────┘ │
│                             │
│ Scene Order = Load Sequence  │
└─────────────────────────────┘

Build-Up - 7 Steps

1

Foundation

What are Scenes in Unity

Concept: Introduce the idea of scenes as separate parts or levels of a game.

In Unity, a scene is like a room or a stage where your game happens. Each scene can have different objects, characters, and settings. For example, one scene might be the main menu, another the first level, and another the game over screen.

Result

You understand that a game is made up of multiple scenes, each representing a different part of the game experience.

Knowing that scenes are separate containers for game content helps you organize your project clearly and manage complexity.

2

Foundation

Opening Build Settings Window

Concept: Show how to access the build settings to manage scenes for the final game.

In Unity, go to the menu bar and click File > Build Settings. This opens a window where you can add scenes to your build and set their order. You can drag scenes into the list or remove them. This list controls what scenes are included when you make your game.

Result

You can open and navigate the build settings window to see and edit the scenes included in your build.

Accessing build settings is the first step to controlling what parts of your game get included and how they load.

3

Intermediate

Adding Scenes to Build Settings

🤔Before reading on: Do you think Unity automatically includes all scenes in your project in the build? Commit to yes or no.

Concept: Explain that scenes must be manually added to the build settings to be included in the final game.

Unity does NOT include all scenes automatically. You must add each scene you want in your game to the build settings list. You can drag scenes from your project folder into the build settings window or click 'Add Open Scenes' to add the currently open scene.

Result

Only the scenes you add to the build settings will be part of your final game build.

Understanding that scenes must be explicitly included prevents missing parts in your game and unexpected behavior.

4

Intermediate

Understanding Scene Order Importance

🤔Before reading on: Does the order of scenes in build settings affect which scene loads first? Commit to yes or no.

Concept: Teach that the order of scenes in build settings determines the starting scene and load sequence.

The first scene in the build settings list is the one Unity loads when the game starts. The order also matters if you use scene indexes in scripts to load scenes. Changing the order changes which scene appears first and how scene indexes map to scenes.

Result

You can control the game's starting point and scene loading by arranging scenes in the build settings order.

Knowing scene order controls the game's flow helps you plan your game structure and avoid loading the wrong scene first.

5

Intermediate

Using Scene Indexes in Scripts

🤔Before reading on: Do you think scene indexes in scripts match the order in build settings or the project folder? Commit to your answer.

Concept: Explain how scene indexes correspond to their position in build settings and how scripts use these indexes to load scenes.

Each scene in build settings has an index starting at 0 for the first scene. In scripts, you can load scenes by their index using SceneManager.LoadScene(index). This index matches the scene's position in build settings, not the project folder or scene name.

Result

You can load scenes by index in your code, relying on the build settings order.

Understanding scene indexes link to build settings order prevents bugs when loading scenes by number.

6

Advanced

Managing Multiple Scenes and Dependencies

🤔Before reading on: Can you include scenes in build settings that are never loaded during gameplay? Commit to yes or no.

Concept: Discuss how to manage many scenes, including optional or additive scenes, and their inclusion in build settings.

You can include scenes in build settings that load only sometimes or additively (on top of others). Even if a scene is not loaded at start, it must be in build settings to be included in the build. Managing dependencies means ensuring all needed scenes are included and ordered properly.

Result

You can organize complex games with many scenes, controlling which load when and how.

Knowing that all used scenes must be in build settings avoids missing content and runtime errors.

7

Expert

Optimizing Build Settings for Performance

🤔Before reading on: Does the order of scenes in build settings affect build size or load times? Commit to yes or no.

Concept: Explain how build settings and scene order can impact build size, load times, and memory usage.

Scenes earlier in the build settings list can be prioritized for faster loading. Removing unused scenes reduces build size. Also, splitting large scenes into smaller ones and loading them additively can improve performance. Unity builds only included scenes, so careful selection and order optimize the final product.

Result

Your game builds faster, runs smoother, and uses less memory by managing build settings wisely.

Understanding build settings impact on performance helps create efficient, professional games.

Under the Hood

When you build your game, Unity looks at the build settings list and packages only those scenes into the final game files. The first scene in the list is set as the entry point. Scene indexes correspond to their position in this list, which scripts use to load scenes by number. Unity does not include scenes not listed, so they are excluded from the build. This system ensures only needed content is included, reducing build size and controlling game flow.

Why designed this way?

Unity separates scene inclusion and order to give developers explicit control over what goes into the build and how the game starts. Automatically including all scenes would bloat builds and cause unwanted content to appear. The order system aligns with scripting needs and allows flexible game flow design. This design balances ease of use with powerful control.

┌───────────────┐       ┌───────────────┐
│ Project Folder│       │ Build Settings│
│ (All Scenes)  │──────▶│ (Included     │
│               │       │  Scenes List) │
└───────────────┘       └───────────────┘
                              │
                              ▼
                    ┌───────────────────┐
                    │ Final Game Build  │
                    │ - Only included   │
                    │   scenes packaged │
                    │ - First scene loads│
                    └───────────────────┘

Myth Busters - 4 Common Misconceptions

Quick: Does Unity automatically include all scenes in your project in the build? Commit to yes or no.

Common Belief: Unity includes every scene in your project automatically when you build the game.

Reality: Only scenes added to the build settings list are included in the final build.

Why it matters: If you assume all scenes are included, you might find parts of your game missing or not working after building.

Quick: Does the order of scenes in build settings affect which scene loads first? Commit to yes or no.

Common Belief: The order of scenes in build settings does not matter; Unity decides the start scene automatically.

Reality: The first scene in the build settings list is the one Unity loads when the game starts.

Why it matters: If you don't set the correct first scene, your game might start on a blank or wrong screen, confusing players.

Quick: Can you load a scene by its name or index interchangeably without issues? Commit to yes or no.

Common Belief: Loading scenes by index or name is the same and always safe.

Reality: Loading by index depends on build settings order; if the order changes, indexes can point to different scenes, causing bugs.

Why it matters: Relying on indexes without managing build settings order can cause wrong scenes to load, breaking game flow.

Quick: Does including unused scenes in build settings have no effect on build size? Commit to yes or no.

Common Belief: Including scenes that are never loaded does not affect the build size or performance.

Reality: All scenes in build settings are included in the build, increasing size even if never loaded.

Why it matters: Unnecessary scenes bloat the build, increasing download size and load times.

Expert Zone

1

Scene order affects not only the start scene but also the scene indexes used in code, so changing order can silently break scene loading.

2

Additive scene loading requires all additive scenes to be in build settings, even if they never load first, to avoid runtime errors.

3

Build settings can be scripted to automate scene inclusion and order, which is useful for large projects with many scenes.

When NOT to use

Build settings and scene order are essential for Unity builds, but for dynamic content loading or asset bundles, you might use Addressables or Asset Bundles instead to load content at runtime without including all scenes in the build.

Production Patterns

In professional projects, teams often automate build settings management with scripts to ensure correct scene order and inclusion. They use scene indexes carefully or prefer loading by scene name to avoid bugs. Large games split content into many scenes and load them additively to optimize memory and performance.

Connections

State Machines

Build settings scene order controls the initial state and transitions between scenes, similar to how state machines manage states and transitions.

Understanding scene order as a state transition sequence helps design predictable game flows and manage complex navigation.

Modular Programming

Scenes act like modules that can be included or excluded in the build, similar to how modular programming organizes code into reusable parts.

Seeing scenes as modules clarifies why explicit inclusion and order matter for building a coherent, maintainable game.

Supply Chain Management

Just as supply chains control which parts arrive and in what order to build a product, build settings control which scenes are included and their loading order.

This connection highlights the importance of planning and sequencing resources to ensure smooth production and delivery.

Common Pitfalls

#1 Forgetting to add a new scene to build settings causes it to be missing in the final game.

Wrong approach:

SceneManager.LoadScene("NewLevel"); // but 'NewLevel' not added to build settings

Correct approach:

Add 'NewLevel' scene to build settings list before building the game.

Root cause:

Assuming Unity includes all scenes automatically without manual addition.

#2 Changing scene order without updating code causes wrong scenes to load by index.

Wrong approach:

SceneManager.LoadScene(1); // expects Level1 but build settings order changed

Correct approach:

Either keep build settings order fixed or load scenes by name: SceneManager.LoadScene("Level1");

Root cause:

Not realizing scene indexes depend on build settings order.

#3 Including unused scenes bloats build size and slows loading.

Wrong approach:

Adding all project scenes to build settings regardless of use.

Correct approach:

Only add scenes that are actually used or loaded during gameplay.

Root cause:

Not understanding that build settings control what is packaged into the final build.

Key Takeaways

Build settings in Unity control which scenes are included in your final game and the order they load.

Only scenes added to build settings are packaged into the build; missing scenes cause runtime errors.

The first scene in build settings is the starting point of your game and determines the initial screen players see.

Scene indexes in scripts correspond to their order in build settings, so changing order can break scene loading by index.

Managing build settings carefully improves game flow, reduces build size, and prevents common bugs.