diff --git a/src/game/level.rs b/src/game/level.rs
deleted file mode 100644
index db6e32e..0000000
--- a/src/game/level.rs
+++ /dev/null
@@ -1,60 +0,0 @@
-
-use bevy::prelude::*;
-use avian3d::prelude::*;
-
-mod target_wall;
-
-pub struct LevelPlugin;
-
-impl Plugin for LevelPlugin
-{
-    fn build(&self, app: &mut App)
-    {
-        app.add_plugins(target_wall::TargetWallPlugin);
-        app.add_systems(Startup, setup_level);
-    }
-}
-
-fn setup_level(
-    mut commands: Commands,
-    mut meshes: ResMut<Assets<Mesh>>,
-    mut materials: ResMut<Assets<StandardMaterial>>,
-) {
-    const GROUND_SIZE: f32 = 100.0;
-
-    // spawn the ground plane
-    commands.spawn((
-        Mesh3d(meshes.add(Plane3d::new(Vec3::Y, Vec2::splat(GROUND_SIZE * 0.5)))),
-        MeshMaterial3d(materials.add(StandardMaterial {
-            base_color: Color::srgb(0.761, 0.698, 0.502),
-            ..default()
-        })),
-        Transform::IDENTITY,
-        Collider::cuboid(GROUND_SIZE, 0.0, GROUND_SIZE),
-        RigidBody::Static,
-    ));
-
-    // spawn a box
-    commands.spawn((
-        Mesh3d(meshes.add(Cuboid::from_corners(
-            Vec3::new(-0.5, -0.5, -0.5), Vec3::new(0.5, 0.5, 0.5)
-        ))),
-        MeshMaterial3d(materials.add(StandardMaterial {
-            base_color: Color::srgb(0.7, 0.1, 0.1),
-            ..default()
-        })),
-        Transform::from_xyz(2.0, 0.5, -5.0),
-        Collider::cuboid(1.0, 1.0, 1.0),
-        RigidBody::Dynamic,
-    ));
-
-    // spawn a light source
-    commands.spawn((
-        DirectionalLight {
-            illuminance: light_consts::lux::AMBIENT_DAYLIGHT,
-            shadows_enabled: true,
-            ..default()
-        },
-        Transform::from_xyz(100.0, 200.0, 100.0).looking_at(Vec3::ZERO, Vec3::Y),
-    ));
-}
diff --git a/src/game/mod.rs b/src/game/mod.rs
index 23ba98d..6328964 100644
--- a/src/game/mod.rs
+++ b/src/game/mod.rs
@@ -1,8 +1,15 @@
 
+use bevy::input::ButtonState;
 use bevy::prelude::*;
+use bevy::input::mouse::MouseButtonInput;
+use avian3d::prelude::*;
 
-mod player;
-mod level;
+use crate::physics::BulletFiredEvent;
+use crate::ui::camera::CameraController;
+use crate::ui::cursor::CursorGrabState;
+
+mod target_wall;
+use target_wall::TargetWallPlugin;
 
 pub struct GamePlugin;
 
@@ -10,7 +17,92 @@ impl Plugin for GamePlugin
 {
     fn build(&self, app: &mut App)
     {
-        app.add_plugins(player::PlayerPlugin);
-        app.add_plugins(level::LevelPlugin);
+        app.add_plugins(TargetWallPlugin);
+
+        app.add_systems(Startup, setup_level);
+
+        app.add_systems(Update, do_shoot_on_left_click
+            .run_if(in_state(CursorGrabState(true)))
+            .run_if(on_event::<MouseButtonInput>))
+            ;
     }
 }
+
+fn setup_level(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
+    const GROUND_SIZE: f32 = 100.0;
+
+    // spawn the camera
+    commands.spawn((
+        CameraController {
+            sensitivity: Vec2::new(0.0007, 0.0007),
+        },
+        Camera3d::default(),
+        Transform::from_xyz(0.0, 1.75, 2.0),
+    ));
+
+    // spawn the ground plane
+    commands.spawn((
+        Mesh3d(meshes.add(Plane3d::new(Vec3::Y, Vec2::splat(GROUND_SIZE * 0.5)))),
+        MeshMaterial3d(materials.add(StandardMaterial {
+            base_color: Color::srgb(0.761, 0.698, 0.502),
+            ..default()
+        })),
+        Transform::IDENTITY,
+        Collider::cuboid(GROUND_SIZE, 0.0, GROUND_SIZE),
+        RigidBody::Static,
+    ));
+
+    // spawn some boxes to shoot at
+    for x in [0.0, 1.5, 3.0]
+    {
+        commands.spawn((
+            Mesh3d(meshes.add(Cuboid::from_corners(
+                Vec3::ZERO, Vec3::ONE,
+            ))),
+            MeshMaterial3d(materials.add(StandardMaterial {
+                base_color: Color::srgb(0.7, 0.1, 0.1),
+                ..default()
+            })),
+            Transform::from_xyz(x, 0.5, -2.0),
+            Collider::cuboid(1.0, 1.0, 1.0),
+            RigidBody::Dynamic,
+        ));
+    }
+
+    // spawn a light source
+    commands.spawn((
+        DirectionalLight {
+            illuminance: light_consts::lux::AMBIENT_DAYLIGHT,
+            shadows_enabled: true,
+            ..default()
+        },
+        Transform::from_xyz(100.0, 200.0, 100.0).looking_at(Vec3::ZERO, Vec3::Y),
+    ));
+}
+
+fn do_shoot_on_left_click(
+    camera_query: Single<&GlobalTransform, With<Camera>>,
+    mut mouse_events: EventReader<MouseButtonInput>,
+    mut bullet_events: EventWriter<BulletFiredEvent>,
+) {
+    let camera_transform = camera_query.into_inner();
+
+    let bullet_fired_event = BulletFiredEvent {
+        position: camera_transform.translation() + Dir3::NEG_X * 2.0,
+        direction: camera_transform.forward(),
+        speed: 200.0,
+        radius: 0.008,
+        density: 11.0,
+    };
+
+    bullet_events.send_batch(mouse_events.read()
+        .filter(|event| event.button == MouseButton::Left)
+        .filter(|event| event.state == ButtonState::Pressed)
+        .map(|_| bullet_fired_event)
+        .collect::<Vec<_>>()
+        );
+}
diff --git a/src/game/player.rs b/src/game/player.rs
deleted file mode 100644
index b364f24..0000000
--- a/src/game/player.rs
+++ /dev/null
@@ -1,68 +0,0 @@
-
-use bevy::prelude::*;
-use bevy::input::{mouse::MouseButtonInput, ButtonState};
-use avian3d::prelude::*;
-
-use crate::physics::BulletFiredEvent;
-use crate::ui::camera::CameraController;
-use crate::ui::cursor::CursorGrabState;
-
-pub struct PlayerPlugin;
-
-impl Plugin for PlayerPlugin
-{
-    fn build(&self, app: &mut App)
-    {
-        app.add_systems(Startup, setup_player);
-        app.add_systems(Update, do_shoot_on_left_click
-            .run_if(in_state(CursorGrabState(true)))
-            .run_if(on_event::<MouseButtonInput>)
-            );
-    }
-}
-
-#[derive(Component)]
-pub struct Player;
-
-fn setup_player(
-    mut commands: Commands,
-) {
-    commands
-        .spawn((
-            Player,
-            Transform::from_xyz(0.0, 1.0, 0.0),
-            Collider::capsule(0.5, 1.0),
-            RigidBody::Kinematic,
-            Dominance(32),
-            Visibility::default(),
-        ))
-        .with_child((
-            CameraController {
-                sensitivity: Vec2::new(0.0007, 0.0007),
-            },
-            Camera3d::default(),
-            Transform::from_xyz(0.0, 0.75, 0.0),
-        ))
-        ;
-}
-
-fn do_shoot_on_left_click(
-    query: Single<&GlobalTransform, With<Camera>>,
-    mut mouse_events: EventReader<MouseButtonInput>,
-    mut bullet_events: EventWriter<BulletFiredEvent>,
-) {
-    let transform = query.into_inner();
-
-    for _ in mouse_events.read()
-        .filter(|event| event.button == MouseButton::Left)
-        .filter(|event| event.state == ButtonState::Pressed)
-    {
-        bullet_events.send(BulletFiredEvent {
-            position: transform.translation() + transform.forward() * 0.5,
-            direction: transform.forward(),
-            radius: 0.008,
-            density: 11.0,
-            velocity: 910.0,
-        });
-    }
-}
diff --git a/src/game/level/target_wall.rs b/src/game/target_wall.rs
similarity index 95%
rename from src/game/level/target_wall.rs
rename to src/game/target_wall.rs
index a4f3285..df29f92 100644
--- a/src/game/level/target_wall.rs
+++ b/src/game/target_wall.rs
@@ -150,6 +150,7 @@ fn setup_target_wall(
 }
 
 fn on_targets_shot(
+    mut commands: Commands,
     mut collision_events: EventReader<CollisionEnded>,
     mut query_set: ParamSet<(
         Query<Entity, With<Bullet>>,
@@ -163,7 +164,7 @@ fn on_targets_shot(
         // between a bullet and a target
         //
         let bullet_query = &mut query_set.p0();
-        let Ok(_) = collision.query_unique(bullet_query) else {
+        let Ok(bullet_entity) = collision.query_unique(bullet_query) else {
             continue; // the collision doesn't involve a bullet
         };
         //
@@ -174,5 +175,9 @@ fn on_targets_shot(
 
         // move the target
         *target_transform = target_resources.random_transform(target_handle);
+
+        // despawn the bullet
+        // TODO: this should be handled by the projectiles system
+        commands.entity(bullet_entity).despawn_recursive();
     }
 }
diff --git a/src/physics/mod.rs b/src/physics/mod.rs
index a08f6bd..bdb339b 100644
--- a/src/physics/mod.rs
+++ b/src/physics/mod.rs
@@ -12,14 +12,14 @@ pub struct PhysicsPlugins;
 
 impl PluginGroup for PhysicsPlugins
 {
-    fn build(self) -> bevy::app::PluginGroupBuilder
+    fn build(self) -> PluginGroupBuilder
     {
         PluginGroupBuilder::start::<Self>()
 
             .add_group(avian3d::PhysicsPlugins::default())
             .add(avian3d::debug_render::PhysicsDebugPlugin::default())
 
-            .add(WorldBoundsPlugin)
             .add(ProjectilesPlugin)
+            .add(WorldBoundsPlugin)
     }
 }
diff --git a/src/physics/projectiles.rs b/src/physics/projectiles.rs
index c9b7e51..524d5bb 100644
--- a/src/physics/projectiles.rs
+++ b/src/physics/projectiles.rs
@@ -2,6 +2,8 @@
 use bevy::prelude::*;
 use avian3d::prelude::*;
 
+use crate::util::ecs::PathTracer;
+
 pub struct ProjectilesPlugin;
 
 impl Plugin for ProjectilesPlugin
@@ -38,14 +40,14 @@ fn setup_projectiles(
     });
 }
 
-#[derive(Event, Debug)]
+#[derive(Event, Copy, Clone, PartialEq, Debug)]
 pub struct BulletFiredEvent
 {
     pub position: Vec3,
     pub direction: Dir3,
+    pub speed: f32,
     pub radius: f32,
     pub density: f32,
-    pub velocity: f32,
 }
 
 #[derive(Component)]
@@ -71,9 +73,10 @@ fn on_bullet_fired_event(
             transform,
             RigidBody::Dynamic,
             ColliderDensity(event.density),
-            LinearVelocity(event.velocity * event.direction),
-            SpeculativeMargin(0.0),
+            SpeculativeMargin(event.radius),
             SweptCcd::LINEAR,
+            LinearVelocity(event.speed * event.direction),
+            PathTracer::default(),
         )
     };
 
diff --git a/src/util/ecs/despawn_timer.rs b/src/util/ecs/despawn_timer.rs
new file mode 100644
index 0000000..5b730b2
--- /dev/null
+++ b/src/util/ecs/despawn_timer.rs
@@ -0,0 +1,30 @@
+
+use bevy::prelude::*;
+
+pub struct DespawnTimerPlugin;
+
+impl Plugin for DespawnTimerPlugin
+{
+    fn build(&self, app: &mut App)
+    {
+        app.add_systems(Update, do_despawn_timer_tick_and_despawn);
+    }
+}
+
+#[derive(Component)]
+pub struct DespawnTimer(pub Timer);
+
+fn do_despawn_timer_tick_and_despawn(
+    mut commands: Commands,
+    mut query: Query<(Entity, &mut DespawnTimer)>,
+    time: Res<Time>,
+) {
+    for (entity, mut timer) in query.iter_mut()
+    {
+        timer.0.tick(time.delta());
+
+        if timer.0.finished() {
+            commands.entity(entity).despawn_recursive();
+        }
+    }
+}
diff --git a/src/util/ecs/mod.rs b/src/util/ecs/mod.rs
new file mode 100644
index 0000000..8cf5302
--- /dev/null
+++ b/src/util/ecs/mod.rs
@@ -0,0 +1,20 @@
+
+mod despawn_timer;
+pub use despawn_timer::*;
+
+mod path_tracer;
+pub use path_tracer::*;
+
+use bevy::app::{PluginGroup, PluginGroupBuilder};
+
+pub struct UtilEcsPlugins;
+
+impl PluginGroup for UtilEcsPlugins
+{
+    fn build(self) -> bevy::app::PluginGroupBuilder
+    {
+        PluginGroupBuilder::start::<Self>()
+            .add(DespawnTimerPlugin)
+            .add(EntityPathTracerPlugin)
+    }
+}
diff --git a/src/util/ecs/path_tracer.rs b/src/util/ecs/path_tracer.rs
new file mode 100644
index 0000000..410e296
--- /dev/null
+++ b/src/util/ecs/path_tracer.rs
@@ -0,0 +1,156 @@
+
+use std::collections::HashMap;
+
+use bevy::prelude::*;
+use avian3d::prelude::*;
+
+use crate::util::physics::CollisionQuery;
+
+const TRACER_PATH_COLOR:  Color = Color::srgb(0.1, 0.7, 0.1);
+const TRACER_HIT_COLOR_X: Color = Color::srgb(0.7, 0.0, 0.0);
+const TRACER_HIT_COLOR_Y: Color = Color::srgb(0.0, 0.7, 0.0);
+const TRACER_HIT_COLOR_Z: Color = Color::srgb(0.0, 0.0, 0.7);
+const TRACER_HIT_RADIUS: f32 = 0.33;
+
+pub struct EntityPathTracerPlugin;
+
+impl Plugin for EntityPathTracerPlugin
+{
+    fn build(&self, app: &mut App)
+    {
+        app.insert_resource(PathTracerResources {
+            tracers: HashMap::new(),
+        });
+
+        app.add_systems(PhysicsSchedule, do_tracer_log_path.in_set(SolverSet::PreSubstep));
+        app.add_systems(PostProcessCollisions, do_tracer_log_collisions);
+        app.add_systems(Last, do_draw_tracers);
+    }
+}
+
+#[derive(Resource)]
+struct PathTracerResources
+{
+    tracers: HashMap<Entity,PathTraceData>,
+}
+
+#[derive(Default, Clone, PartialEq)]
+pub struct PathTraceData
+{
+    path: Vec<Vec3>,
+    collisions: Vec<Isometry3d>,
+}
+
+impl PathTraceData
+{
+    fn log_position(&mut self, isometry: Isometry3d)
+    {
+        self.path.push(isometry.translation.into());
+    }
+
+    fn log_collision(&mut self, isometry: Isometry3d)
+    {
+        self.collisions.push(isometry);
+    }
+}
+
+#[derive(Component, Clone, PartialEq)]
+#[allow(unused)]
+pub enum PathTracer
+{
+    Transient(PathTraceData),
+    Persistent,
+}
+
+impl Default for PathTracer
+{
+    fn default() -> Self
+    {
+        PathTracer::Transient(PathTraceData {
+            path: Vec::new(),
+            collisions: Vec::new(),
+        })
+    }
+}
+
+impl PathTracer
+{
+    fn mut_trace_data<'a>(
+        &'a mut self,
+        entity: &Entity,
+        resources: &'a mut ResMut<PathTracerResources>
+    ) -> &'a mut PathTraceData
+    {
+        match self {
+            PathTracer::Transient(trace_data) => trace_data,
+            PathTracer::Persistent => resources.tracers.get_mut(entity).unwrap(),
+        }
+    }
+
+    fn get_trace_data<'a>(
+        &'a self,
+        entity: &Entity,
+        resources: &'a Res<PathTracerResources>
+    ) -> &'a PathTraceData
+    {
+        match self {
+            PathTracer::Transient(trace_data) => trace_data,
+            PathTracer::Persistent => resources.tracers.get(entity).unwrap(),
+        }
+    }
+}
+
+fn do_tracer_log_path(
+    mut query: Query<(Entity, &mut PathTracer, &GlobalTransform)>,
+    mut resources: ResMut<PathTracerResources>,
+) {
+    for (entity, mut tracer, transform) in query.iter_mut()
+    {
+        let trace_data = tracer.mut_trace_data(&entity, &mut resources);
+        trace_data.log_position(transform.compute_transform().to_isometry());
+    }
+}
+
+fn do_tracer_log_collisions(
+    mut query: Query<(Entity, &mut PathTracer, &GlobalTransform)>,
+    mut collision_events: EventReader<CollisionStarted>,
+    mut resources: ResMut<PathTracerResources>,
+) {
+    for collision in collision_events.read()
+    {
+        let Ok((entity, mut tracer, transform)) = collision.query_unique(&mut query) else {
+            continue;
+        };
+
+        let trace_data = tracer.mut_trace_data(&entity, &mut resources);
+        trace_data.log_collision(transform.compute_transform().to_isometry());
+    }
+}
+
+fn do_draw_tracers(
+    query: Query<(Entity, &PathTracer)>,
+    resources: Res<PathTracerResources>,
+    mut gizmos: Gizmos,
+) {
+    use std::f32::consts::FRAC_PI_2;
+    let isometry_x = Isometry3d::from_rotation(Quat::from_rotation_x(FRAC_PI_2));
+    let isometry_y = Isometry3d::from_rotation(Quat::from_rotation_y(FRAC_PI_2));
+    let isometry_z = Isometry3d::from_rotation(Quat::from_rotation_z(FRAC_PI_2));
+
+    for (entity, tracer) in query.iter()
+    {
+        let trace_data = tracer.get_trace_data(&entity, &resources);
+
+        for window in trace_data.path.windows(2)
+        {
+            gizmos.line(window[0], window[1], TRACER_PATH_COLOR);
+        }
+
+        for isometry in trace_data.collisions.iter()
+        {
+            gizmos.circle(*isometry * isometry_x, TRACER_HIT_RADIUS, TRACER_HIT_COLOR_X);
+            gizmos.circle(*isometry * isometry_y, TRACER_HIT_RADIUS, TRACER_HIT_COLOR_Y);
+            gizmos.circle(*isometry * isometry_z, TRACER_HIT_RADIUS, TRACER_HIT_COLOR_Z);
+        }
+    }
+}
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 501a09c..20dad89 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -1,2 +1,21 @@
 
+use bevy::app::{PluginGroup, PluginGroupBuilder};
+
+pub mod ecs;
+use ecs::UtilEcsPlugins;
+
 pub mod physics;
+use physics::UtilPhysicsPlugins;
+
+pub struct UtilPlugins;
+
+impl PluginGroup for UtilPlugins
+{
+    fn build(self) -> bevy::app::PluginGroupBuilder
+    {
+        PluginGroupBuilder::start::<Self>()
+
+            .add_group(UtilEcsPlugins)
+            .add_group(UtilPhysicsPlugins)
+    }
+}
diff --git a/src/util/physics/mod.rs b/src/util/physics/mod.rs
index fb16957..451be86 100644
--- a/src/util/physics/mod.rs
+++ b/src/util/physics/mod.rs
@@ -1,3 +1,15 @@
 
+use bevy::app::{PluginGroup, PluginGroupBuilder};
+
 mod collision_query;
 pub use collision_query::*;
+
+pub struct UtilPhysicsPlugins;
+
+impl PluginGroup for UtilPhysicsPlugins
+{
+    fn build(self) -> PluginGroupBuilder
+    {
+        PluginGroupBuilder::start::<Self>()
+    }
+}