Bevy starter template (0.15)

main.rs

use bevy::diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin};
use bevy::prelude::*;

fn main() {
    let mut app = App::new();
    app.add_plugins((
        DefaultPlugins
            .set(ImagePlugin::default_nearest())
            .set(WindowPlugin {
                primary_window: Some(Window {
                    title: "My Game".to_string(),
                    resolution: (500.0, 500.0).into(),
                    resizable: true,
                    focused: true,
                    ..Default::default()
                }),
                ..Default::default()
            }),
        LogDiagnosticsPlugin::default(),
        FrameTimeDiagnosticsPlugin,
    ))
    .add_systems(Startup, setup)
    .add_systems(Update, close_on_esc);
    app.run();
}

fn setup(mut commands: Commands) {
    commands.spawn(Camera2d);
}

pub fn close_on_esc(
    mut commands: Commands,
    focused_windows: Query<(Entity, &Window)>,
    input: Res<ButtonInput<KeyCode>>,
) {
    for (window, focus) in focused_windows.iter() {
        if !focus.focused {
            continue;
        }

        if input.just_pressed(KeyCode::Escape) {
            commands.entity(window).despawn();
        }
    }
}