diff --git a/justfile b/justfile
index 36ffc51..4cd64d1 100644
--- a/justfile
+++ b/justfile
@@ -4,3 +4,6 @@ tb_setup_mac:
     mkdir -p "$HOME/Library/Application Support/TrenchBroom/games/hedz" | true
     ln -s $(pwd)/trenchbroom/hedz/hedz.fgd "$HOME/Library/Application Support/TrenchBroom/games/hedz/hedz.fgd" | true
     ln -s $(pwd)/trenchbroom/hedz/GameConfig.cfg "$HOME/Library/Application Support/TrenchBroom/games/hedz/GameConfig.cfg" | true
+
+dbg:
+    cargo r --features dbg
\ No newline at end of file
diff --git a/src/backpack/backpack_ui.rs b/src/backpack/backpack_ui.rs
new file mode 100644
index 0000000..2fa142f
--- /dev/null
+++ b/src/backpack/backpack_ui.rs
@@ -0,0 +1,329 @@
+use super::{BackbackSwapEvent, Backpack, BackpackHead};
+use crate::heads_ui::HeadsImages;
+use bevy::prelude::*;
+
+static HEAD_SLOTS: usize = 5;
+
+#[derive(Event, Clone, Copy, Reflect, PartialEq)]
+pub enum BackpackAction {
+    Left,
+    Right,
+    Swap,
+    OpenClose,
+}
+
+#[derive(Component, Default)]
+struct BackpackMarker;
+
+#[derive(Component, Default)]
+struct BackpackCountText;
+
+#[derive(Component, Default)]
+struct HeadSelector(pub usize);
+
+#[derive(Component, Default)]
+struct HeadImage(pub usize);
+
+#[derive(Component, Default)]
+struct HeadDamage(pub usize);
+
+#[derive(Resource, Default, Debug)]
+struct BackpackUiState {
+    heads: [Option<BackpackHead>; 5],
+    scroll: usize,
+    count: usize,
+    current_slot: usize,
+    open: bool,
+}
+
+impl BackpackUiState {
+    fn relative_current_slot(&self) -> usize {
+        self.current_slot.saturating_sub(self.scroll)
+    }
+}
+
+pub fn plugin(app: &mut App) {
+    app.init_resource::<BackpackUiState>();
+    app.add_systems(Startup, setup);
+    app.add_systems(
+        Update,
+        (update, sync_on_change, update_visibility, update_count),
+    );
+    app.add_observer(swap_head_inputs);
+}
+
+fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
+    let bg = asset_server.load("ui/head_bg.png");
+    let regular = asset_server.load("ui/head_regular.png");
+    let damage = asset_server.load("ui/head_damage.png");
+    let selector = asset_server.load("ui/selector.png");
+
+    commands
+        .spawn((
+            Name::new("backpack"),
+            BackpackMarker,
+            Visibility::Hidden,
+            Node {
+                position_type: PositionType::Absolute,
+                top: Val::Px(20.0),
+                right: Val::Px(20.0),
+                height: Val::Px(74.0),
+                ..default()
+            },
+        ))
+        .with_children(|parent| {
+            for i in 0..HEAD_SLOTS {
+                spawn_head_ui(
+                    parent,
+                    bg.clone(),
+                    regular.clone(),
+                    selector.clone(),
+                    damage.clone(),
+                    i,
+                );
+            }
+        });
+
+    commands.spawn((
+        Text::new("0"),
+        BackpackCountText,
+        TextFont {
+            font: asset_server.load("font.ttf"),
+            font_size: 34.0,
+            ..default()
+        },
+        TextColor(Color::Srgba(Srgba::rgb(0., 1., 0.))),
+        TextLayout::new_with_justify(JustifyText::Center),
+        Node {
+            position_type: PositionType::Absolute,
+            top: Val::Px(20.0),
+            right: Val::Px(20.0),
+            ..default()
+        },
+    ));
+}
+
+fn spawn_head_ui(
+    parent: &mut ChildBuilder,
+    bg: Handle<Image>,
+    regular: Handle<Image>,
+    selector: Handle<Image>,
+    damage: Handle<Image>,
+    head_slot: usize,
+) {
+    const SIZE: f32 = 90.0;
+    const DAMAGE_SIZE: f32 = 74.0;
+
+    parent
+        .spawn((Node {
+            position_type: PositionType::Relative,
+            justify_content: JustifyContent::Center,
+            align_items: AlignItems::Center,
+            width: Val::Px(SIZE),
+            ..default()
+        },))
+        .with_children(|parent| {
+            parent.spawn((
+                Name::new("selector"),
+                Node {
+                    position_type: PositionType::Absolute,
+                    bottom: Val::Px(-30.0),
+                    ..default()
+                },
+                Visibility::Hidden,
+                ImageNode::new(selector).with_flip_y(),
+                HeadSelector(head_slot),
+            ));
+            parent.spawn((
+                Name::new("bg"),
+                Node {
+                    position_type: PositionType::Absolute,
+                    ..default()
+                },
+                ImageNode::new(bg),
+            ));
+            parent.spawn((
+                Name::new("head"),
+                Node {
+                    position_type: PositionType::Absolute,
+                    ..default()
+                },
+                ImageNode::default(),
+                Visibility::Hidden,
+                HeadImage(head_slot),
+            ));
+            parent.spawn((
+                Name::new("rings"),
+                Node {
+                    position_type: PositionType::Absolute,
+                    ..default()
+                },
+                ImageNode::new(regular),
+            ));
+            parent
+                .spawn((
+                    Name::new("health"),
+                    Node {
+                        height: Val::Px(DAMAGE_SIZE),
+                        width: Val::Px(DAMAGE_SIZE),
+                        ..default()
+                    },
+                ))
+                .with_children(|parent| {
+                    parent
+                        .spawn((
+                            Name::new("damage_ring"),
+                            HeadDamage(head_slot),
+                            Node {
+                                position_type: PositionType::Absolute,
+                                display: Display::Block,
+                                overflow: Overflow::clip(),
+                                top: Val::Px(0.),
+                                left: Val::Px(0.),
+                                right: Val::Px(0.),
+                                height: Val::Percent(25.),
+                                ..default()
+                            },
+                        ))
+                        .with_child(ImageNode::new(damage));
+                });
+        });
+}
+
+fn update_visibility(
+    state: Res<BackpackUiState>,
+    mut backpack: Query<&mut Visibility, (With<BackpackMarker>, Without<BackpackCountText>)>,
+    mut count: Query<&mut Visibility, (Without<BackpackMarker>, With<BackpackCountText>)>,
+) {
+    if state.is_changed() {
+        for mut vis in backpack.iter_mut() {
+            *vis = if state.open {
+                Visibility::Visible
+            } else {
+                Visibility::Hidden
+            };
+        }
+
+        for mut vis in count.iter_mut() {
+            *vis = if !state.open {
+                Visibility::Visible
+            } else {
+                Visibility::Hidden
+            };
+        }
+    }
+}
+
+fn update_count(
+    state: Res<BackpackUiState>,
+    text: Query<Entity, With<BackpackCountText>>,
+    mut writer: TextUiWriter,
+) {
+    if state.is_changed() {
+        let Some(text) = text.iter().next() else {
+            return;
+        };
+
+        *writer.text(text, 0) = state.count.to_string();
+    }
+}
+
+fn update(
+    state: Res<BackpackUiState>,
+    heads_images: Res<HeadsImages>,
+    mut head_image: Query<(&HeadImage, &mut Visibility, &mut ImageNode), Without<HeadSelector>>,
+    mut head_damage: Query<(&HeadDamage, &mut Node), Without<HeadSelector>>,
+    mut head_selector: Query<(&HeadSelector, &mut Visibility), Without<HeadImage>>,
+) {
+    if state.is_changed() {
+        for (HeadImage(head), mut vis, mut image) in head_image.iter_mut() {
+            if let Some(head) = &state.heads[*head] {
+                *vis = Visibility::Inherited;
+                image.image = heads_images.heads[head.head].clone();
+            } else {
+                *vis = Visibility::Hidden;
+            }
+        }
+        for (HeadDamage(head), mut node) in head_damage.iter_mut() {
+            if let Some(head) = &state.heads[*head] {
+                node.height = Val::Percent((1. - head.health) * 100.0);
+            }
+        }
+
+        for (HeadSelector(head), mut vis) in head_selector.iter_mut() {
+            *vis = if *head == state.relative_current_slot() {
+                Visibility::Inherited
+            } else {
+                Visibility::Hidden
+            };
+        }
+    }
+}
+
+fn swap_head_inputs(
+    trigger: Trigger<BackpackAction>,
+    backpack: Res<Backpack>,
+    mut commands: Commands,
+    mut state: ResMut<BackpackUiState>,
+) {
+    if state.count == 0 {
+        return;
+    }
+
+    let action = *trigger.event();
+    if action == BackpackAction::OpenClose {
+        state.open = !state.open;
+    }
+
+    if !state.open {
+        return;
+    }
+
+    let mut changed = false;
+    if action == BackpackAction::Left {
+        if state.current_slot > 0 {
+            state.current_slot -= 1;
+            changed = true;
+        }
+    }
+    if action == BackpackAction::Right {
+        if state.current_slot < state.count.saturating_sub(1) {
+            state.current_slot += 1;
+            changed = true;
+        }
+    }
+    if action == BackpackAction::Swap {
+        commands.trigger(BackbackSwapEvent(state.current_slot));
+    }
+
+    if changed {
+        sync(&backpack, &mut state);
+    }
+}
+
+fn sync_on_change(backpack: Res<Backpack>, mut state: ResMut<BackpackUiState>) {
+    if backpack.is_changed() {
+        sync(&backpack, &mut state);
+    }
+}
+
+fn sync(backpack: &Res<Backpack>, state: &mut ResMut<BackpackUiState>) {
+    state.count = backpack.heads.len();
+
+    state.scroll = state.scroll.min(state.count.saturating_sub(HEAD_SLOTS));
+
+    if state.current_slot >= state.scroll + HEAD_SLOTS {
+        state.scroll = state.current_slot.saturating_sub(HEAD_SLOTS - 1);
+    }
+    if state.current_slot < state.scroll {
+        state.scroll = state.current_slot;
+    }
+
+    for i in 0..HEAD_SLOTS {
+        if let Some(head) = backpack.heads.get(i + state.scroll) {
+            state.heads[i] = Some(*head);
+        } else {
+            state.heads[i] = None;
+        }
+    }
+}
diff --git a/src/backpack/mod.rs b/src/backpack/mod.rs
new file mode 100644
index 0000000..56085c5
--- /dev/null
+++ b/src/backpack/mod.rs
@@ -0,0 +1,38 @@
+mod backpack_ui;
+
+use crate::heads_ui::HEAD_COUNT;
+use bevy::prelude::*;
+
+pub use backpack_ui::BackpackAction;
+
+#[derive(Clone, Copy, Debug)]
+pub struct BackpackHead {
+    pub head: usize,
+    pub health: f32,
+}
+
+#[derive(Resource, Default)]
+pub struct Backpack {
+    pub heads: Vec<BackpackHead>,
+}
+
+#[derive(Event)]
+pub struct BackbackSwapEvent(pub usize);
+
+pub fn plugin(app: &mut App) {
+    app.add_plugins(backpack_ui::plugin);
+
+    app.add_systems(Startup, setup);
+}
+
+fn setup(mut commands: Commands) {
+    commands.insert_resource(Backpack {
+        heads: (0usize..HEAD_COUNT)
+            .into_iter()
+            .map(|i| BackpackHead {
+                head: i,
+                health: 1.,
+            })
+            .collect(),
+    });
+}
diff --git a/src/controls.rs b/src/controls.rs
index 68f26e9..f8a744a 100644
--- a/src/controls.rs
+++ b/src/controls.rs
@@ -1,4 +1,4 @@
-use crate::{heads_ui::SwapHead, shooting::TriggerState};
+use crate::{backpack::BackpackAction, heads_ui::SelectActiveHead, shooting::TriggerState};
 use bevy::{
     input::{
         ButtonState,
@@ -86,10 +86,22 @@ fn gamepad_controls(
         commands.trigger(TriggerState::Inactive);
     }
     if gamepad.just_pressed(GamepadButton::LeftTrigger) {
-        commands.trigger(SwapHead::Left);
+        commands.trigger(SelectActiveHead::Left);
     }
     if gamepad.just_pressed(GamepadButton::RightTrigger) {
-        commands.trigger(SwapHead::Right);
+        commands.trigger(SelectActiveHead::Right);
+    }
+    if gamepad.just_pressed(GamepadButton::DPadLeft) {
+        commands.trigger(BackpackAction::Left);
+    }
+    if gamepad.just_pressed(GamepadButton::DPadRight) {
+        commands.trigger(BackpackAction::Right);
+    }
+    if gamepad.just_pressed(GamepadButton::DPadDown) {
+        commands.trigger(BackpackAction::Swap);
+    }
+    if gamepad.just_pressed(GamepadButton::DPadUp) {
+        commands.trigger(BackpackAction::OpenClose);
     }
 
     if controls
@@ -129,11 +141,24 @@ fn keyboard_controls(
         direction += Vec2::X;
     }
 
+    if keyboard.just_pressed(KeyCode::KeyB) {
+        commands.trigger(BackpackAction::OpenClose);
+    }
+    if keyboard.just_pressed(KeyCode::Enter) {
+        commands.trigger(BackpackAction::Swap);
+    }
+    if keyboard.just_pressed(KeyCode::Comma) {
+        commands.trigger(BackpackAction::Left);
+    }
+    if keyboard.just_pressed(KeyCode::Period) {
+        commands.trigger(BackpackAction::Right);
+    }
+
     if keyboard.just_pressed(KeyCode::KeyQ) {
-        commands.trigger(SwapHead::Left);
+        commands.trigger(SelectActiveHead::Left);
     }
     if keyboard.just_pressed(KeyCode::KeyE) {
-        commands.trigger(SwapHead::Right);
+        commands.trigger(SelectActiveHead::Right);
     }
 
     controls.keyboard_state.move_dir = direction;
diff --git a/src/heads_ui.rs b/src/heads_ui.rs
index 8d56daa..f13e41a 100644
--- a/src/heads_ui.rs
+++ b/src/heads_ui.rs
@@ -1,9 +1,14 @@
+use crate::{
+    backpack::{BackbackSwapEvent, Backpack, BackpackHead},
+    player::head_id_to_str,
+};
 use bevy::prelude::*;
 
-use crate::player::head_id_to_str;
+pub static HEAD_COUNT: usize = 18;
+static HEAD_SLOTS: usize = 5;
 
 #[derive(Event, Reflect)]
-pub enum SwapHead {
+pub enum SelectActiveHead {
     Left,
     Right,
 }
@@ -21,12 +26,12 @@ struct HeadImage(pub usize);
 struct HeadDamage(pub usize);
 
 #[derive(Resource, Default)]
-struct HeadsImages {
-    heads: Vec<Handle<Image>>,
+pub struct HeadsImages {
+    pub heads: Vec<Handle<Image>>,
 }
 
 #[derive(Resource, Default)]
-struct ActiveHeads {
+pub struct ActiveHeads {
     heads: [Option<usize>; 5],
     current_slot: usize,
 }
@@ -37,8 +42,9 @@ pub struct HeadChanged(pub usize);
 pub fn plugin(app: &mut App) {
     app.register_type::<HeadDamage>();
     app.add_systems(Startup, setup);
-    app.add_systems(Update, (update, swap_head_test));
-    app.add_observer(on_swap_head);
+    app.add_systems(Update, update);
+    app.add_observer(on_select_active_head);
+    app.add_observer(on_swap_backpack);
 }
 
 fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
@@ -56,7 +62,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
             ..default()
         })
         .with_children(|parent| {
-            for i in 0..5 {
+            for i in 0..HEAD_SLOTS {
                 spawn_head_ui(
                     parent,
                     bg.clone(),
@@ -68,7 +74,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
             }
         });
 
-    let heads = (0usize..18)
+    let heads = (0usize..HEAD_COUNT)
         .into_iter()
         .map(|i| asset_server.load(format!("ui/heads/{}.png", head_id_to_str(i))))
         .collect();
@@ -87,7 +93,7 @@ fn spawn_head_ui(
     regular: Handle<Image>,
     selector: Handle<Image>,
     damage: Handle<Image>,
-    head: usize,
+    head_slot: usize,
 ) {
     const SIZE: f32 = 90.0;
     const DAMAGE_SIZE: f32 = 74.0;
@@ -109,7 +115,7 @@ fn spawn_head_ui(
                 },
                 Visibility::Hidden,
                 ImageNode::new(selector),
-                HeadSelector(head),
+                HeadSelector(head_slot),
             ));
             parent.spawn((
                 Node {
@@ -127,7 +133,7 @@ fn spawn_head_ui(
                 },
                 ImageNode::default(),
                 Visibility::Hidden,
-                HeadImage(head),
+                HeadImage(head_slot),
             ));
             parent.spawn((
                 Node {
@@ -145,7 +151,7 @@ fn spawn_head_ui(
                 .with_children(|parent| {
                     parent
                         .spawn((
-                            HeadDamage(head),
+                            HeadDamage(head_slot),
                             Node {
                                 position_type: PositionType::Absolute,
                                 display: Display::Block,
@@ -162,25 +168,6 @@ fn spawn_head_ui(
         });
 }
 
-fn swap_head_test(
-    mut commands: Commands,
-    mut active: ResMut<ActiveHeads>,
-    keyboard: Res<ButtonInput<KeyCode>>,
-) {
-    if keyboard.just_pressed(KeyCode::Comma) {
-        let slot = active.current_slot;
-        let current = active.heads[active.current_slot].unwrap();
-        active.heads[slot] = Some((current + 17) % 18);
-        commands.trigger(HeadChanged(active.heads[slot].unwrap()));
-    }
-    if keyboard.just_pressed(KeyCode::Period) {
-        let slot = active.current_slot;
-        let current = active.heads[active.current_slot].unwrap();
-        active.heads[slot] = Some((current + 1) % 18);
-        commands.trigger(HeadChanged(active.heads[slot].unwrap()));
-    }
-}
-
 fn update(
     res: Res<ActiveHeads>,
     heads_images: Res<HeadsImages>,
@@ -206,15 +193,46 @@ fn update(
     }
 }
 
-fn on_swap_head(trigger: Trigger<SwapHead>, mut commands: Commands, mut res: ResMut<ActiveHeads>) {
+fn on_select_active_head(
+    trigger: Trigger<SelectActiveHead>,
+    mut commands: Commands,
+    mut res: ResMut<ActiveHeads>,
+) {
     match trigger.event() {
-        SwapHead::Right => {
-            res.current_slot = (res.current_slot + 1) % 5;
+        SelectActiveHead::Right => {
+            res.current_slot = (res.current_slot + 1) % HEAD_SLOTS;
         }
-        SwapHead::Left => {
-            res.current_slot = (res.current_slot + 4) % 5;
+        SelectActiveHead::Left => {
+            res.current_slot = (res.current_slot + (HEAD_SLOTS - 1)) % HEAD_SLOTS;
         }
     }
 
     commands.trigger(HeadChanged(res.heads[res.current_slot].unwrap()));
 }
+
+fn on_swap_backpack(
+    trigger: Trigger<BackbackSwapEvent>,
+    mut commands: Commands,
+    mut res: ResMut<ActiveHeads>,
+    mut backpack: ResMut<Backpack>,
+) {
+    let backpack_slot = trigger.event().0;
+
+    let head = backpack.heads.get(backpack_slot).unwrap();
+
+    let current_active_slot = res.current_slot;
+
+    let current_active_head = res.heads[current_active_slot];
+    res.heads[current_active_slot] = Some(head.head);
+
+    if let Some(old_active) = current_active_head {
+        backpack.heads[backpack_slot] = BackpackHead {
+            head: old_active,
+            health: 1.,
+        };
+    } else {
+        backpack.heads.remove(backpack_slot);
+    }
+
+    commands.trigger(HeadChanged(res.heads[res.current_slot].unwrap()));
+}
diff --git a/src/main.rs b/src/main.rs
index f9f3381..7cc2389 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 mod aim;
 mod alien;
+mod backpack;
 mod billboards;
 mod camera;
 mod cash;
@@ -94,6 +95,7 @@ fn main() {
     app.add_plugins(controls::plugin);
     app.add_plugins(sounds::plugin);
     app.add_plugins(camera::plugin);
+    app.add_plugins(backpack::plugin);
 
     app.insert_resource(AmbientLight {
         color: Color::WHITE,
@@ -104,10 +106,7 @@ fn main() {
 
     app.add_systems(Startup, (write_trenchbroom_config, music));
     app.add_systems(PostStartup, setup_scene);
-    app.add_systems(
-        Update,
-        (set_materials_unlit, set_tonemapping, set_shadows, spawn_box),
-    );
+    app.add_systems(Update, (set_materials_unlit, set_tonemapping, set_shadows));
 
     app.run();
 }
@@ -137,24 +136,6 @@ fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
     ));
 }
 
-fn spawn_box(
-    mut commands: Commands,
-    mut meshes: ResMut<Assets<Mesh>>,
-    mut materials: ResMut<Assets<StandardMaterial>>,
-    keys: Res<ButtonInput<KeyCode>>,
-) {
-    if keys.just_pressed(KeyCode::Enter) {
-        commands.spawn((
-            RigidBody::Dynamic,
-            Collider::cuboid(5.0, 5.0, 5.0),
-            AngularVelocity(Vec3::new(2.5, 3.5, 1.5)),
-            Mesh3d(meshes.add(Cuboid::from_length(5.0))),
-            MeshMaterial3d(materials.add(Color::srgb_u8(124, 144, 255))),
-            Transform::from_xyz(0.0, 50.0, 0.0),
-        ));
-    }
-}
-
 fn music(asset_server: Res<AssetServer>, mut commands: Commands) {
     commands.spawn((
         AudioPlayer::new(asset_server.load("sfx/music/02.ogg")),