Start

From cargo new to a main menu

Seven steps. The first two already give you a window, a main menu, settings that save and Esc to pause.

01
Add the crate
Depend on the engine with its defaults off and pick features: physics (avian3d) and fps (the first-person controller). Name bevy yourself with no features, so its derive macros resolve; the engine picks every feature. Your dev feature turns the debug tools on.
Placeholder Not on crates.io yet: a path dependency for now.
Cargo.toml
```
[dependencies.engine]
path = "../engine"
default-features = false
features = ["physics", "fps"]

[dependencies]
bevy = { version = "=0.19.1", default-features = false }

[features]
# cargo run / cargo test keep every debug tool
default = ["dev"]
dev = ["engine/devtools", "engine/trace"]
```
02
Write main.rs
One call builds the window or headless app, CLI flags, data and asset folders, settings, the main menu and the pause menu. Add your game as a plugin and put its flow under AppState::InGame.
src/main.rs
```
use engine::prelude::*;

fn main() {
    engine::app(
        GameInfo::new("orbs", "Orbs").tagline("Collect them all."),
    )
    .add_plugins(MyGamePlugin)
    .run();
}
```

Add your settings

Your section is a serde struct. It is saved next to the core settings in settings.json, 0.6 s after the last change and on exit. A corrupt file is moved aside and defaults load.

src/main.rs

#[derive(Resource, Serialize, Deserialize, Default, Clone, PartialEq)]
#[serde(default)]
struct MySettings { difficulty: usize, assist: bool }

fn main() {
    engine::app(GameInfo::new("id", "Title"))
        .add_plugins((engine::settings::SettingsPlugin::<MySettings>::default(), MyPlugin))
        .run();
}

Put them on screen

Each FieldDef is a row on the generated settings screen: Toggle, Slider, Choice, Cards or Swatches, on the tab you name. Reset tab restores the defaults.

courier/src/settings.rs

app.register_setting(FieldDef {
    key: "assist",
    tab: "Gameplay",
    label: "Steering assist",
    hint: "More grip and calmer steering at speed. Off: the bike slides and drifts.",
    kind: FieldKind::Toggle,
    get: |w| b(s(w).assist),
    set: |w, v| s_mut(w).assist = v > 0.5,
})

Brand the menus

One accent colour re-themes the whole kit. MenuConfig sets the main and pause items, a side panel and a pause header. Build config structs with ..default(), so new engine fields never break your game.

courier/src/menus.rs

.insert_resource(Theme::default().with_accent(Color::srgb(1.0, 0.78, 0.22)))
.insert_resource(MenuConfig {
    eyebrow: "Hover-bike parcel delivery",
    main_items: vec![
        ("Start shift", MenuAction::Open("shift")),
        ("Records", MenuAction::Open("records")),
        ("Settings", MenuAction::Settings),
        ("Quit", MenuAction::Quit),
    ],
    ..default()
})

Run it, test it

Dev builds take engine flags such as --play and --headless. The control port lets a test or an agent press keys, read state and save screenshots from a hidden window.

terminal

cargo run --example minimal --features fps      # the smallest game: ground, cube, camera
cargo run -- --play                               # skip the main menu (dev builds)
cargo run -- --headless                           # no window, for tests

07
Ship without the tools
Build with --no-default-features. The debug tools live in the ashlar crates (control port, MCP, trace); the packaging script fails if any of them is still in the tree or the binary, and copies only the binary and assets.
terminal
```
scripts/package.sh --manifest Cargo.toml --package mygame --bin mygame \
    --features "physics fps" --assets assets
cargo tree -p <pkg> --no-default-features --features "<ship features>" -e normal | grep ashlar
# prints nothing
```

From cargo new to a main menu

Add the crate

Write main.rs

Add your settings

Put them on screen

Brand the menus

Run it, test it

Ship without the tools

Paused

Accent colour