Ladies and gentlemen... we have a bouncing bird

src/bin/flappy/main.rs

@@ -4,9 +4,13 @@ fn main() {
     App::new()
         .add_plugins(BaseGamePlugin { name: "flappy bird (with rewind)".into() })
         .add_systems(Startup, init_bird)
+        .add_systems(Update, flap)
         .run();
 }
 
+#[derive(Component)]
+struct Bird;
+
 fn init_bird(
     mut commands: Commands,
     server: Res<AssetServer>,
@@ -29,8 +33,21 @@ fn init_bird(
         let mass = (
             RigidBody::Dynamic,
             Collider::capsule(1.0, 1.0),
-            Mass(5.0),
+            Mass(1.0),
         );
 
-        commands.spawn((name, mesh, material, mass, t));
+        let force = ExternalForce::default().with_persistence(false);
+
+        commands.spawn((name, mesh, material, mass, t, Bird, force));
+}
+
+fn flap(
+    keyboard: Res<ButtonInput<KeyCode>>,
+    mut bird: Query<(&Transform, &mut ExternalForce), With<Bird>>,
+) {
+    if keyboard.just_pressed(KeyCode::Space) {
+        bird.iter_mut().for_each(|(t, mut f)| {
+            f.apply_force(t.rotation * Vec3::NEG_Z * 1000.0);
+        });
+    }
 }