diff --git a/.gitignore b/.gitignore
index 96b244a..7e17b2b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /target
 /.direnv
 /logs
+/.idea
diff --git a/.roo/mcp.json b/.roo/mcp.json
new file mode 100644
index 0000000..7001130
--- /dev/null
+++ b/.roo/mcp.json
@@ -0,0 +1,3 @@
+{
+  "mcpServers": {}
+}
\ No newline at end of file
diff --git a/README.md b/README.md
index 4166dbc..8b33cbf 100644
--- a/README.md
+++ b/README.md
@@ -47,35 +47,35 @@ nix develop --command bash -c "cargo build"
     *   ~~Use Bevy's `States` (e.g., `Playing`, `GameOver`).~~
     *   ~~Transition to `GameOver` when `PlayerLives` reaches zero.~~
     *   ~~In the `GameOver` state: stop enemy spawning, stop player controls, display a "Game Over" message (using `bevy_ui`), potentially offer a restart option.~~
-*   **Scoring:**
-    *   Add a `Score` resource.
-    *   Increment the score in `check_bullet_collisions` when an enemy is hit.
+*   ~~**Scoring:**~~ **(DONE)**
+    *   ~~Add a `Score` resource.~~
+    *   ~~Increment the score in `check_bullet_collisions` when an enemy is hit.~~
     *   Consider different point values for different enemy types or hitting enemies during dives later.
-*   **Levels/Stages:**
-    *   Add a `CurrentStage` resource.
-    *   Define criteria for clearing a stage (e.g., destroying all enemies in a wave/formation).
-    *   Implement logic to advance to the next stage, potentially increasing difficulty (enemy speed, firing rate, different formations).
+*   ~~**Levels/Stages:**~~ **(DONE)**
+    *   ~~Add a `CurrentStage` resource.~~
+    *   ~~Define criteria for clearing a stage (e.g., destroying all enemies in a wave/formation).~~
+    *   ~~Implement logic to advance to the next stage, potentially increasing difficulty (enemy speed, firing rate, different formations).~~
 
 **2. Enemy Behavior - Formations & Attack Patterns:**
 
 *   **Enemy Formations:** This is a core Galaga feature.
-    *   Define target positions for the enemy formation on screen.
-    *   Give enemies an `Entering` state/component: They fly onto the screen following predefined paths (curves, waypoints).
-    *   Give enemies a `Formation` state/component: Once they reach their target position, they stop and hold formation.
+    *   ~~Define target positions for the enemy formation on screen.~~ **(DONE)**
+    *   ~~Give enemies an `Entering` state/component: They fly onto the screen following predefined paths (curves, waypoints).~~ **(DONE - Basic linear path implemented)**
+    *   Give enemies a `Formation` state/component: Once they reach their target position, they stop and hold formation. **(DONE - Stop implemented by removing FormationTarget)**
 *   **Enemy Attack Dives:**
-    *   Give enemies an `Attacking` state/component.
-    *   Periodically trigger enemies in the formation to switch to the `Attacking` state.
-    *   Define attack paths (swooping dives towards the player area).
-    *   Make enemies fire bullets (downwards or towards the player) during their dives.
-    *   After an attack dive, enemies could return to their formation position or fly off-screen.
+    *   ~~Give enemies an `Attacking` state/component.~~ **(DONE)**
+    *   ~~Periodically trigger enemies in the formation to switch to the `Attacking` state.~~ **(DONE - Random selection after formation complete)**
+    *   ~~Define attack paths (swooping dives towards the player area).~~ **(DONE - Basic swoop towards center implemented)**
+    *   ~~Make enemies fire bullets (downwards or towards the player) during their dives.~~ **(DONE - Downward)**
+    *   After an attack dive, enemies could return to their formation position or fly off-screen. **(Fly off-screen implemented)**
 *   **Enemy Variety:**
-    *   Introduce different types of enemies (e.g., using different components or an enum).
-    *   Assign different behaviors, point values, and maybe sprites to each type.
+    *   ~~Introduce different types of enemies (e.g., using different components or an enum).~~ **(DONE - Added EnemyType enum and field)**
+    *   ~~Assign different behaviors, point values, and maybe sprites to each type.~~ **(DONE - Behaviors, points & color based on type)**
 
 **3. Advanced Galaga Mechanics:**
 
 *   **Boss Galaga & Capture Beam:**
-    *   Create a "Boss" enemy type.
+    *   ~~Create a "Boss" enemy type.~~ **(DONE - Added to Enum, handled in matches)**
     *   Implement the tractor beam attack (visual effect, player capture logic).
     *   Player needs a `Captured` state.
     *   Logic for the Boss to return captured ships to the formation.
diff --git a/src/bullet.rs b/src/bullet.rs
new file mode 100644
index 0000000..2cd46a4
--- /dev/null
+++ b/src/bullet.rs
@@ -0,0 +1,113 @@
+use bevy::prelude::*;
+
+use crate::components::{Bullet, Enemy, EnemyBullet, EnemyType};
+use crate::constants::{
+    BULLET_ENEMY_COLLISION_THRESHOLD, BULLET_SIZE, BULLET_SPEED, ENEMY_BULLET_PLAYER_COLLISION_THRESHOLD,
+    ENEMY_BULLET_SIZE, ENEMY_BULLET_SPEED, WINDOW_HEIGHT,
+};
+use crate::resources::{PlayerLives, PlayerRespawnTimer, Score};
+use crate::game_state::AppState;
+use crate::components::Player; // Needed for check_enemy_bullet_player_collisions
+use crate::components::Invincible; // Needed for check_enemy_bullet_player_collisions
+
+// --- Player Bullet Systems ---
+
+pub fn move_bullets(
+    mut query: Query<(Entity, &mut Transform), With<Bullet>>,
+    time: Res<Time>,
+    mut commands: Commands,
+) {
+    for (entity, mut transform) in query.iter_mut() {
+        transform.translation.y += BULLET_SPEED * time.delta_seconds();
+
+        if transform.translation.y > WINDOW_HEIGHT / 2.0 + BULLET_SIZE.y {
+            commands.entity(entity).despawn();
+        }
+    }
+}
+
+pub fn check_bullet_collisions(
+    mut commands: Commands,
+    bullet_query: Query<(Entity, &Transform), With<Bullet>>,
+    enemy_query: Query<(Entity, &Transform, &Enemy), With<Enemy>>, // Fetch Enemy component too
+    mut score: ResMut<Score>,                                      // Add Score resource
+) {
+    for (bullet_entity, bullet_transform) in bullet_query.iter() {
+        for (enemy_entity, enemy_transform, enemy) in enemy_query.iter() {
+            // Get Enemy component
+            let distance = bullet_transform
+                .translation
+                .distance(enemy_transform.translation);
+
+            if distance < BULLET_ENEMY_COLLISION_THRESHOLD {
+                commands.entity(bullet_entity).despawn();
+                commands.entity(enemy_entity).despawn();
+                // Increment score based on enemy type
+                let points = match enemy.enemy_type {
+                    EnemyType::Grunt => 100,
+                    EnemyType::Boss => 100, // Same points as Grunt for now
+                };
+                score.value += points;
+                println!("Enemy hit by player bullet! Score: {}", score.value); // Log score update
+                break; // Bullet only hits one enemy
+            }
+        }
+    }
+}
+
+// --- Enemy Bullet Systems ---
+
+pub fn move_enemy_bullets(
+    mut commands: Commands,
+    time: Res<Time>,
+    mut query: Query<(Entity, &mut Transform), With<EnemyBullet>>,
+) {
+    for (entity, mut transform) in query.iter_mut() {
+        transform.translation.y -= ENEMY_BULLET_SPEED * time.delta_seconds();
+
+        // Despawn if off screen (bottom)
+        if transform.translation.y < -WINDOW_HEIGHT / 2.0 - ENEMY_BULLET_SIZE.y {
+            commands.entity(entity).despawn();
+        }
+    }
+}
+
+// Check collisions between enemy bullets and the player
+pub fn check_enemy_bullet_player_collisions(
+    mut commands: Commands,
+    mut lives: ResMut<PlayerLives>,
+    mut respawn_timer: ResMut<PlayerRespawnTimer>,
+    mut next_state: ResMut<NextState<AppState>>,
+    // Player query matching the run_if condition (player exists and is vulnerable)
+    player_query: Query<(Entity, &Transform), (With<Player>, Without<Invincible>)>,
+    enemy_bullet_query: Query<(Entity, &Transform), With<EnemyBullet>>,
+) {
+    if let Ok((player_entity, player_transform)) = player_query.get_single() {
+        for (bullet_entity, bullet_transform) in enemy_bullet_query.iter() {
+            let distance = player_transform
+                .translation
+                .distance(bullet_transform.translation);
+
+            if distance < ENEMY_BULLET_PLAYER_COLLISION_THRESHOLD {
+                println!("Player hit by enemy bullet!");
+                commands.entity(bullet_entity).despawn(); // Despawn bullet
+
+                lives.count = lives.count.saturating_sub(1);
+                println!("Lives remaining: {}", lives.count);
+
+                commands.entity(player_entity).despawn(); // Despawn player
+
+                if lives.count > 0 {
+                    respawn_timer.timer.reset();
+                    respawn_timer.timer.unpause();
+                    println!("Respawn timer started.");
+                } else {
+                    println!("GAME OVER!");
+                    next_state.set(AppState::GameOver);
+                }
+                // Break because the player can only be hit once per frame
+                break;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/components.rs b/src/components.rs
new file mode 100644
index 0000000..6b02234
--- /dev/null
+++ b/src/components.rs
@@ -0,0 +1,57 @@
+use bevy::prelude::*;
+use std::time::Duration; // Needed for Timer in Player
+
+// --- Components ---
+#[derive(Component)]
+pub struct Player {
+    pub speed: f32,
+    pub shoot_cooldown: Timer,
+}
+
+#[derive(Component)]
+pub struct Bullet;
+
+#[derive(Component, Clone, Copy, PartialEq, Eq, Debug)] // Added derive for common traits
+pub enum EnemyType {
+    Grunt,
+    Boss, // Added Boss type
+}
+
+#[derive(Component)]
+pub struct Enemy {
+    pub enemy_type: EnemyType, // Add type field
+    pub shoot_cooldown: Timer,
+}
+
+#[derive(Component)]
+pub struct Invincible {
+    pub timer: Timer,
+}
+
+#[derive(Component)]
+pub struct FormationTarget {
+    pub position: Vec3,
+}
+
+// Enum defining different ways an enemy can attack
+#[derive(Component, Clone, Copy, PartialEq, Debug)]
+pub enum AttackPattern {
+    SwoopDive,      // Original pattern: dive towards center, then off screen
+    DirectDive,     // Dive straight down
+    Kamikaze(Vec3), // Dive towards a specific target location (e.g., player's last known position) - Needs target Vec3
+    // Add more patterns later (e.g., FigureEight, Looping)
+}
+
+#[derive(Component, Clone, PartialEq, Debug)] // Added Debug derive
+pub enum EnemyState {
+    Entering,                // Flying onto the screen towards formation target
+    InFormation,             // Holding position in the formation
+    Attacking(AttackPattern), // Diving towards the player using a specific pattern
+}
+
+#[derive(Component)]
+pub struct EnemyBullet;
+
+// Game Over UI Component (might move to ui.rs later if more UI exists)
+#[derive(Component)]
+pub struct GameOverUI;
\ No newline at end of file
diff --git a/src/constants.rs b/src/constants.rs
new file mode 100644
index 0000000..2b5bd8e
--- /dev/null
+++ b/src/constants.rs
@@ -0,0 +1,33 @@
+use bevy::math::Vec2;
+
+// --- Constants ---
+pub const WINDOW_WIDTH: f32 = 600.0;
+pub const WINDOW_HEIGHT: f32 = 800.0;
+pub const PLAYER_SPEED: f32 = 300.0;
+pub const BULLET_SPEED: f32 = 500.0;
+pub const ENEMY_SPEED: f32 = 100.0;
+pub const PLAYER_SIZE: Vec2 = Vec2::new(30.0, 30.0);
+pub const ENEMY_SIZE: Vec2 = Vec2::new(40.0, 40.0);
+pub const BULLET_SIZE: Vec2 = Vec2::new(5.0, 15.0);
+// Player bullet
+pub const ENEMY_BULLET_SIZE: Vec2 = Vec2::new(8.0, 8.0);
+// Enemy bullet
+pub const ENEMY_BULLET_SPEED: f32 = 300.0;
+pub const ENEMY_SHOOT_INTERVAL: f32 = 1.5;
+// Formation constants
+const FORMATION_ROWS: usize = 4;
+pub const FORMATION_COLS: usize = 8;
+pub const FORMATION_ENEMY_COUNT: usize = FORMATION_ROWS * FORMATION_COLS;
+pub const FORMATION_X_SPACING: f32 = 60.0;
+pub const FORMATION_Y_SPACING: f32 = 50.0;
+pub const FORMATION_BASE_Y: f32 = WINDOW_HEIGHT / 2.0 - 150.0;
+// Top area for formation
+pub const STARTING_LIVES: u32 = 3;
+pub const PLAYER_RESPAWN_DELAY: f32 = 2.0;
+pub const PLAYER_INVINCIBILITY_DURATION: f32 = 2.0;
+// Collision thresholds
+pub const BULLET_ENEMY_COLLISION_THRESHOLD: f32 = (BULLET_SIZE.x + ENEMY_SIZE.x) * 0.5;
+// 22.5
+pub const PLAYER_ENEMY_COLLISION_THRESHOLD: f32 = (PLAYER_SIZE.x + ENEMY_SIZE.x) * 0.5;
+// 35.0
+pub const ENEMY_BULLET_PLAYER_COLLISION_THRESHOLD: f32 = (ENEMY_BULLET_SIZE.x + PLAYER_SIZE.x) * 0.5;
diff --git a/src/enemy.rs b/src/enemy.rs
new file mode 100644
index 0000000..5cacf51
--- /dev/null
+++ b/src/enemy.rs
@@ -0,0 +1,368 @@
+use bevy::prelude::*;
+use std::time::Duration;
+
+use crate::components::{Enemy, EnemyBullet, EnemyState, EnemyType, FormationTarget};
+use crate::constants::{ // Added WINDOW_WIDTH
+    ENEMY_BULLET_PLAYER_COLLISION_THRESHOLD, ENEMY_BULLET_SIZE, ENEMY_BULLET_SPEED,
+    ENEMY_SHOOT_INTERVAL, ENEMY_SIZE, ENEMY_SPEED, FORMATION_BASE_Y, FORMATION_COLS,
+    FORMATION_ENEMY_COUNT, FORMATION_X_SPACING, FORMATION_Y_SPACING, WINDOW_HEIGHT, WINDOW_WIDTH,
+};
+use crate::resources::{
+    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState, PlayerLives,
+    PlayerRespawnTimer, StageConfigurations, // Make sure StageConfigurations is imported if not already
+};
+use crate::game_state::AppState;
+
+pub fn spawn_enemies(
+    mut commands: Commands,
+    time: Res<Time>,
+    mut timer: ResMut<EnemySpawnTimer>,
+    mut stage: ResMut<CurrentStage>,
+    mut formation_state: ResMut<FormationState>,
+    stage_configs: Res<StageConfigurations>, // Use imported name
+) {
+    // Get current stage config, looping if stage number exceeds defined configs
+    let config_index = (stage.number as usize - 1) % stage_configs.stages.len();
+    let current_config = &stage_configs.stages[config_index];
+    let stage_enemy_count = current_config.enemy_count;
+
+    // Tick the timer every frame
+    timer.timer.tick(time.delta());
+
+    // Only spawn if we haven't spawned the full formation for this stage yet
+    // AND the timer just finished this frame
+    if formation_state.total_spawned_this_stage < stage_enemy_count
+        && timer.timer.just_finished()
+    {
+        let slot_index = formation_state.next_slot_index;
+
+        // Ensure slot_index is within bounds of the formation layout
+        if slot_index >= current_config.formation_layout.positions.len() {
+             println!("Warning: slot_index {} out of bounds for formation layout '{}' (size {})",
+                slot_index, current_config.formation_layout.name, current_config.formation_layout.positions.len());
+             // Optionally, reset the timer and skip spawning this frame, or handle differently
+             timer.timer.reset();
+             return;
+        }
+
+        // Get target position from the stage's formation layout
+        let target_pos = current_config.formation_layout.positions[slot_index];
+
+        // Spawn position (random at the top) - Corrected to use WINDOW_WIDTH
+        let spawn_x = (fastrand::f32() - 0.5) * (WINDOW_WIDTH - ENEMY_SIZE.x);
+        let spawn_y = WINDOW_HEIGHT / 2.0 + ENEMY_SIZE.y / 2.0; // Spawn slightly above screen
+
+        // Determine enemy type (can be randomized or based on stage config later)
+        let enemy_type = EnemyType::Grunt;
+
+        // Determine sprite color based on type
+        let sprite_color = match enemy_type {
+            EnemyType::Grunt => Color::rgb(1.0, 0.2, 0.2),
+            EnemyType::Boss => Color::rgb(0.8, 0.2, 1.0),
+        };
+
+        commands.spawn((
+            SpriteBundle {
+                sprite: Sprite {
+                    color: sprite_color,
+                    custom_size: Some(ENEMY_SIZE),
+                    ..default()
+                },
+                transform: Transform::from_translation(Vec3::new(spawn_x, spawn_y, 0.0)),
+                ..default()
+            },
+            Enemy {
+                enemy_type,
+                // Use shoot interval from stage config
+                shoot_cooldown: Timer::new(
+                    Duration::from_secs_f32(current_config.enemy_shoot_interval),
+                    TimerMode::Once,
+                ),
+            },
+            FormationTarget { position: target_pos },
+            EnemyState::Entering,
+        ));
+
+        // Use stage_enemy_count for cycling index
+        formation_state.next_slot_index = (slot_index + 1) % stage_enemy_count;
+        formation_state.total_spawned_this_stage += 1;
+
+        // Mark that we are now waiting for enemies to be cleared
+        stage.waiting_for_clear = true;
+
+        // Reset timer only if we are still spawning more enemies for the formation
+        if formation_state.total_spawned_this_stage < stage_enemy_count {
+            timer.timer.reset();
+        } else {
+            println!(
+                "Full formation ({}) spawned for Stage {}",
+                current_config.formation_layout.name, stage.number
+            );
+        }
+    }
+}
+
+pub fn move_enemies(
+    mut entering_query: Query<
+        (Entity, &mut Transform, &FormationTarget, &mut EnemyState),
+        (With<Enemy>, With<FormationTarget>),
+    >,
+    mut attacking_query: Query<
+        (Entity, &mut Transform, &EnemyState, &Enemy), // Add &Enemy here
+        (With<Enemy>, Without<FormationTarget>),
+    >, // Query potential attackers
+    time: Res<Time>,
+    mut commands: Commands,
+    stage: Res<CurrentStage>,
+    stage_configs: Res<StageConfigurations>, // Add stage configurations
+) {
+    // Get current stage config for speed multiplier
+    let config_index = (stage.number as usize - 1) % stage_configs.stages.len();
+    let current_config = &stage_configs.stages[config_index];
+    let speed_multiplier = current_config.enemy_speed_multiplier;
+
+    // Calculate speeds for this frame
+    let base_speed = ENEMY_SPEED * speed_multiplier;
+    let attack_speed = base_speed * 1.5; // Attackers are faster
+    let arrival_threshold = base_speed * time.delta_seconds() * 1.1; // Threshold for reaching formation target
+
+    // --- Handle Entering Enemies ---
+    for (entity, mut transform, target, mut state) in entering_query.iter_mut() {
+        // Ensure we only process Entering state here, though query filters it mostly
+        if *state == EnemyState::Entering {
+            let current_pos = transform.translation;
+            let target_pos = target.position;
+            let direction = target_pos - current_pos;
+            let distance = direction.length();
+
+            if distance < arrival_threshold {
+                // Arrived at target
+                transform.translation = target_pos;
+                commands.entity(entity).remove::<FormationTarget>(); // Remove target component
+                *state = EnemyState::InFormation; // Change state
+                println!(
+                    "Enemy {:?} reached formation target and is now InFormation.",
+                    entity
+                );
+            } else {
+                // Move towards target using base_speed
+                let move_delta = direction.normalize() * base_speed * time.delta_seconds();
+                transform.translation += move_delta;
+            }
+        }
+    }
+
+    // --- Handle Attacking Enemies ---
+    // Note: attack_speed calculated above using multiplier
+    for (entity, mut transform, state, _enemy) in attacking_query.iter_mut() {
+
+        // Match on the specific attack pattern using matches! and then get the pattern
+        if matches!(state, EnemyState::Attacking(_)) {
+             if let EnemyState::Attacking(pattern) = state { // Get the pattern safely now
+            let delta_seconds = time.delta_seconds();
+
+            match pattern {
+                AttackPattern::SwoopDive => {
+                    // Original Swooping Dive Logic
+                    let vertical_movement = attack_speed * delta_seconds;
+                    let horizontal_speed_factor = 0.5;
+                    let horizontal_movement = if transform.translation.x < 0.0 {
+                        attack_speed * horizontal_speed_factor * delta_seconds
+                    } else if transform.translation.x > 0.0 {
+                        -attack_speed * horizontal_speed_factor * delta_seconds
+                    } else { 0.0 };
+
+                    transform.translation.y -= vertical_movement;
+                    transform.translation.x += horizontal_movement;
+
+                    // Prevent overshooting center
+                    if (transform.translation.x > 0.0 && transform.translation.x + horizontal_movement < 0.0) ||
+                       (transform.translation.x < 0.0 && transform.translation.x + horizontal_movement > 0.0) {
+                        transform.translation.x = 0.0;
+                    }
+                }
+                AttackPattern::DirectDive => {
+                    // Move straight down
+                    transform.translation.y -= attack_speed * delta_seconds;
+                }
+                AttackPattern::Kamikaze(target_pos) => {
+                    // Move towards the target position
+                    let direction = *target_pos - transform.translation;
+                    let distance = direction.length();
+                    let kamikaze_threshold = attack_speed * delta_seconds * 1.1; // Threshold to stop near target
+
+                    if distance > kamikaze_threshold {
+                        let move_delta = direction.normalize() * attack_speed * delta_seconds;
+                        transform.translation += move_delta;
+                    } else {
+                        // Optionally stop or continue past target - for now, just stop moving towards it
+                        // Could also despawn here if desired upon reaching target
+                    }
+                }
+                // Add cases for other patterns here
+             } // Close inner if let
+            } // Closes match enemy.enemy_type
+        } // Closes if *state == EnemyState::Attacking
+
+        // Despawn if off screen (This should be inside the loop)
+        if transform.translation.y < -WINDOW_HEIGHT / 2.0 - ENEMY_SIZE.y {
+            println!(
+                "Despawning enemy {:?} that went off screen.", // Generic message as it could be InFormation or Attacking
+                entity
+            );
+            commands.entity(entity).despawn();
+            // TODO: Later, attacking enemies might return to formation or loop
+        }
+    } // Closes for loop
+}
+
+// System to check if all spawned enemies have reached their formation position
+pub fn check_formation_complete(
+    mut formation_state: ResMut<FormationState>,
+    enemy_query: Query<&EnemyState, With<Enemy>>,
+    mut attack_dive_timer: ResMut<AttackDiveTimer>,
+    stage: Res<CurrentStage>, // Need current stage
+    stage_configs: Res<StageConfigurations>, // Need stage configs
+) {
+    // Only run the check if the formation isn't already marked as complete
+    if !formation_state.formation_complete {
+        // Get current stage config
+        let config_index = (stage.number as usize - 1) % stage_configs.stages.len();
+        let current_config = &stage_configs.stages[config_index];
+        let stage_enemy_count = current_config.enemy_count;
+
+        // Check if all enemies for *this stage* have been spawned
+        if formation_state.total_spawned_this_stage == stage_enemy_count {
+            // Check if any enemies are still in the Entering state
+            let mut any_entering = false;
+            for state in enemy_query.iter() {
+                // Use matches! macro for safety
+                if matches!(state, EnemyState::Entering) {
+                    any_entering = true;
+                    break;
+                }
+            }
+
+            // If all spawned and none are entering, formation is complete
+            if !any_entering {
+                 println!(
+                    "Formation complete for Stage {}! Setting attack timer. (Spawned={})",
+                    stage.number, formation_state.total_spawned_this_stage
+                );
+                formation_state.formation_complete = true;
+
+                // Set timer duration based on stage config
+                let dive_interval = Duration::from_secs_f32(current_config.attack_dive_interval);
+                attack_dive_timer.timer.set_duration(dive_interval);
+                attack_dive_timer.timer.reset();
+                attack_dive_timer.timer.unpause();
+                println!("Attack timer set to {:?} duration, unpaused and reset.", dive_interval);
+            }
+        }
+    }
+}
+
+use crate::components::AttackPattern; // Import the new enum
+use crate::components::Player; // Import Player for Kamikaze target
+
+pub fn trigger_attack_dives(
+    mut timer: ResMut<AttackDiveTimer>,
+    time: Res<Time>,
+    mut enemy_query: Query<(Entity, &mut EnemyState), With<Enemy>>, // Renamed for clarity
+    formation_state: Res<FormationState>,
+    stage: Res<CurrentStage>, // Need current stage
+    stage_configs: Res<StageConfigurations>, // Need stage configs
+    player_query: Query<&Transform, With<Player>>, // Need player position for Kamikaze
+) {
+    timer.timer.tick(time.delta());
+
+    // Only proceed if the timer finished AND the formation is complete
+    if timer.timer.just_finished() && formation_state.formation_complete {
+        // Find all enemies currently in formation
+        let mut available_enemies: Vec<Entity> = Vec::new();
+        // Get the current stage config
+        let config_index = (stage.number as usize - 1) % stage_configs.stages.len();
+        let current_config = &stage_configs.stages[config_index];
+
+        // Find all enemies currently in formation
+        let mut available_enemies: Vec<Entity> = Vec::new();
+        for (entity, state) in enemy_query.iter() {
+            // Check the state correctly
+            if matches!(state, EnemyState::InFormation) {
+                available_enemies.push(entity);
+            }
+        }
+
+        // If there are enemies available, pick one randomly
+        if !available_enemies.is_empty() && !current_config.attack_patterns.is_empty() {
+            let random_index = fastrand::usize(..available_enemies.len());
+            let chosen_entity = available_enemies[random_index];
+
+            // Select a random attack pattern for this stage
+            let pattern_index = fastrand::usize(..current_config.attack_patterns.len());
+            let mut selected_pattern = current_config.attack_patterns[pattern_index]; // Copy the pattern
+
+            // If Kamikaze, get player position (if player exists)
+            if let AttackPattern::Kamikaze(_) = selected_pattern {
+                if let Ok(player_transform) = player_query.get_single() {
+                     selected_pattern = AttackPattern::Kamikaze(player_transform.translation);
+                } else {
+                    // Fallback if player doesn't exist (e.g., just died)
+                    selected_pattern = AttackPattern::DirectDive; // Or SwoopDive
+                    println!("Kamikaze target not found, falling back to DirectDive");
+                }
+            }
+
+
+            // Get the chosen enemy's state mutably and change it
+            if let Ok((_, mut state)) = enemy_query.get_mut(chosen_entity) {
+                println!("Enemy {:?} starting attack dive with pattern {:?}!", chosen_entity, selected_pattern);
+                *state = EnemyState::Attacking(selected_pattern); // Set state with pattern
+                // Timer duration is handled elsewhere (e.g., check_formation_complete)
+            }
+        }
+    }
+}
+
+pub fn enemy_shoot(
+    mut commands: Commands,
+    time: Res<Time>,
+    // Query attacking enemies: need their transform and mutable Enemy component for the timer
+    mut enemy_query: Query<(&Transform, &mut Enemy, &EnemyState), Without<FormationTarget>>, // Query remains the same
+) {
+    for (transform, mut enemy, state) in enemy_query.iter_mut() {
+        // Only shoot if in any Attacking state (pattern doesn't matter for shooting)
+        if matches!(state, EnemyState::Attacking(_)) { // Use matches! macro
+            enemy.shoot_cooldown.tick(time.delta());
+            if enemy.shoot_cooldown.finished() {
+                // println!("Enemy {:?} firing!", transform.translation); // Less verbose logging
+                let bullet_start_pos = transform.translation
+                    - Vec3::Y * (ENEMY_SIZE.y / 2.0 + ENEMY_BULLET_SIZE.y / 2.0);
+
+                commands.spawn((
+                    SpriteBundle {
+                        sprite: Sprite {
+                            color: Color::rgb(1.0, 0.5, 0.5),
+                            custom_size: Some(ENEMY_BULLET_SIZE),
+                            ..default()
+                        },
+                        transform: Transform::from_translation(bullet_start_pos),
+                        ..default()
+                    },
+                    EnemyBullet,
+                ));
+
+                // Reset the timer for the next shot
+                enemy.shoot_cooldown.reset();
+            }
+        }
+    }
+}
+
+// Check collisions between enemy bullets and the player
+// Moved to player.rs as it affects player state directly
+
+// New run condition: Check if the formation is complete
+pub fn is_formation_complete(formation_state: Res<FormationState>) -> bool {
+    formation_state.formation_complete
+}
\ No newline at end of file
diff --git a/src/game_state.rs b/src/game_state.rs
new file mode 100644
index 0000000..e771ffb
--- /dev/null
+++ b/src/game_state.rs
@@ -0,0 +1,68 @@
+use bevy::prelude::*;
+use crate::components::{Bullet, Enemy, GameOverUI}; // Import necessary components
+
+// --- Game States ---
+#[derive(Clone, Eq, PartialEq, Debug, Hash, Default, States)]
+pub enum AppState {
+    #[default]
+    Playing,
+    GameOver,
+}
+
+// --- Game Over UI ---
+
+pub fn setup_game_over_ui(mut commands: Commands) {
+    println!("Entering GameOver state. Setting up UI.");
+    commands.spawn((
+        TextBundle::from_section(
+            "GAME OVER",
+            TextStyle {
+                font_size: 100.0,
+                color: Color::WHITE,
+                ..default()
+            },
+        )
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            align_self: AlignSelf::Center,
+            justify_self: JustifySelf::Center,
+            top: Val::Percent(40.0), // Center vertically roughly
+            ..default()
+        }),
+        GameOverUI, // Tag the UI element
+    ));
+    // TODO: Add "Press R to Restart" text later
+}
+
+pub fn cleanup_game_over_ui(mut commands: Commands, query: Query<Entity, With<GameOverUI>>) {
+    println!("Exiting GameOver state. Cleaning up UI.");
+    for entity in query.iter() {
+        commands.entity(entity).despawn_recursive();
+    }
+}
+
+// --- Cleanup ---
+
+// Cleanup system when exiting the Playing state
+pub fn cleanup_game_entities(
+    mut commands: Commands,
+    bullet_query: Query<Entity, With<Bullet>>,
+    enemy_bullet_query: Query<Entity, With<crate::components::EnemyBullet>>, // Need to specify crate::components
+    enemy_query: Query<Entity, With<Enemy>>,
+    // Optionally despawn player too, or handle separately if needed for restart
+    // player_query: Query<Entity, With<Player>>,
+) {
+    println!("Exiting Playing state. Cleaning up game entities.");
+    for entity in bullet_query.iter() {
+        commands.entity(entity).despawn();
+    }
+     for entity in enemy_bullet_query.iter() { // Also despawn enemy bullets
+        commands.entity(entity).despawn();
+    }
+    for entity in enemy_query.iter() {
+        commands.entity(entity).despawn();
+    }
+    // for entity in player_query.iter() {
+    //     commands.entity(entity).despawn();
+    // }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index c561ff6..8a1ba75 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,441 +1,136 @@
-use bevy::prelude::*; // Removed unused AppExit
+use bevy::prelude::*;
 use std::time::Duration;
-// --- Game States ---
-#[derive(Clone, Eq, PartialEq, Debug, Hash, Default, States)]
-enum AppState {
-    #[default]
-    Playing,
-    GameOver,
-}
-// --- Constants ---
-const WINDOW_WIDTH: f32 = 600.0;
-const WINDOW_HEIGHT: f32 = 800.0;
-const PLAYER_SPEED: f32 = 300.0;
-const BULLET_SPEED: f32 = 500.0;
-const ENEMY_SPEED: f32 = 100.0;
-const PLAYER_SIZE: Vec2 = Vec2::new(30.0, 30.0);
-const ENEMY_SIZE: Vec2 = Vec2::new(40.0, 40.0);
-const BULLET_SIZE: Vec2 = Vec2::new(5.0, 15.0);
 
-const STARTING_LIVES: u32 = 3;
-const PLAYER_RESPAWN_DELAY: f32 = 2.0;
-const PLAYER_INVINCIBILITY_DURATION: f32 = 2.0;
+pub mod components;
+pub mod constants;
+pub mod resources;
+pub mod game_state;
+pub mod player;
+pub mod enemy;
+pub mod bullet;
+pub mod stage;
+pub mod systems;
 
-// Collision thresholds
-const BULLET_ENEMY_COLLISION_THRESHOLD: f32 = (BULLET_SIZE.x + ENEMY_SIZE.x) * 0.5; // 22.5
-const PLAYER_ENEMY_COLLISION_THRESHOLD: f32 = (PLAYER_SIZE.x + ENEMY_SIZE.x) * 0.5; // 35.0
-
-// --- Components ---
-#[derive(Component)]
-struct Player {
-    speed: f32,
-    shoot_cooldown: Timer,
-}
-
-#[derive(Component)]
-struct Bullet;
-
-#[derive(Component)]
-struct Enemy;
-
-#[derive(Component)]
-struct Invincible {
-    timer: Timer,
-}
-
-// --- Resources ---
-#[derive(Resource)]
-struct EnemySpawnTimer {
-    timer: Timer,
-}
-
-#[derive(Resource)]
-struct PlayerLives {
-    count: u32,
-}
-
-#[derive(Resource)]
-struct PlayerRespawnTimer {
-    timer: Timer,
-}
-
-// --- Game Over UI ---
-
-#[derive(Component)]
-struct GameOverUI;
-
-fn setup_game_over_ui(mut commands: Commands) {
-   println!("Entering GameOver state. Setting up UI.");
-   commands.spawn((
-       TextBundle::from_section(
-           "GAME OVER",
-           TextStyle {
-               font_size: 100.0,
-               color: Color::WHITE,
-               ..default()
-           },
-       )
-       .with_style(Style {
-           position_type: PositionType::Absolute,
-           align_self: AlignSelf::Center,
-           justify_self: JustifySelf::Center,
-           top: Val::Percent(40.0), // Center vertically roughly
-           ..default()
-       }),
-       GameOverUI, // Tag the UI element
-   ));
-   // TODO: Add "Press R to Restart" text later
-}
-
-fn cleanup_game_over_ui(mut commands: Commands, query: Query<Entity, With<GameOverUI>>) {
-    println!("Exiting GameOver state. Cleaning up UI.");
-   for entity in query.iter() {
-       commands.entity(entity).despawn_recursive();
-   }
-}
-
-// --- Cleanup ---
-
-fn cleanup_game_entities(
-   mut commands: Commands,
-   bullet_query: Query<Entity, With<Bullet>>,
-   enemy_query: Query<Entity, With<Enemy>>,
-   // Optionally despawn player too, or handle separately if needed for restart
-   // player_query: Query<Entity, With<Player>>,
-) {
-   println!("Exiting Playing state. Cleaning up game entities.");
-   for entity in bullet_query.iter() {
-       commands.entity(entity).despawn();
-   }
-   for entity in enemy_query.iter() {
-       commands.entity(entity).despawn();
-   }
-   // for entity in player_query.iter() {
-   //     commands.entity(entity).despawn();
-   // }
-}
+use constants::{PLAYER_RESPAWN_DELAY, STARTING_LIVES, WINDOW_HEIGHT, WINDOW_WIDTH};
+use resources::{ // Added StageConfigurations
+    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState, PlayerLives,
+    PlayerRespawnTimer, Score, StageConfigurations,
+};
+use game_state::{
+    cleanup_game_entities, cleanup_game_over_ui, setup_game_over_ui, AppState,
+};
+use player::{
+    check_player_enemy_collisions, manage_invincibility, move_player, player_shoot,
+    respawn_player,
+};
+use enemy::{
+    check_formation_complete, enemy_shoot, is_formation_complete, move_enemies, spawn_enemies,
+    trigger_attack_dives,
+};
+use bullet::{
+    check_bullet_collisions, check_enemy_bullet_player_collisions, move_bullets,
+    move_enemy_bullets,
+};
+use stage::check_stage_clear;
+use systems::{player_exists, player_vulnerable, setup, should_respawn_player, update_window_title};
 
 fn main() {
-    App::new() // Start App builder
-        .init_state::<AppState>() // Initialize the AppState *after* App::new()
+    App::new()
+        .init_state::<AppState>() // Initialize the AppState
         .insert_resource(ClearColor(Color::rgb(0.0, 0.0, 0.0)))
         .add_plugins(DefaultPlugins.set(WindowPlugin {
             primary_window: Some(Window {
-                title: "Galaga :: Lives: 3".into(), // Initial title
+                title: "Galaga :: Stage: 1 Lives: 3 Score: 0".into(), // Initial title
                 resolution: (WINDOW_WIDTH, WINDOW_HEIGHT).into(),
                 ..default()
             }),
             ..default()
         }))
         // Add Resources
-        .insert_resource(PlayerLives { count: STARTING_LIVES })
+        .insert_resource(PlayerLives {
+            count: STARTING_LIVES,
+        })
         .insert_resource(PlayerRespawnTimer {
-             // Start paused and finished
-            timer: Timer::new(Duration::from_secs_f32(PLAYER_RESPAWN_DELAY), TimerMode::Once)
+            timer: Timer::new(
+                Duration::from_secs_f32(PLAYER_RESPAWN_DELAY),
+                TimerMode::Once,
+            ),
         })
         .insert_resource(EnemySpawnTimer {
             timer: Timer::new(Duration::from_secs_f32(0.5), TimerMode::Repeating),
         })
+        .insert_resource(Score { value: 0 })
+        .insert_resource(CurrentStage {
+            number: 1,
+            waiting_for_clear: false,
+        })
+        .insert_resource(FormationState {
+            next_slot_index: 0,
+            total_spawned_this_stage: 0,
+            formation_complete: false,
+        })
+        .insert_resource(StageConfigurations::default()) // Add stage configurations
+        .insert_resource(AttackDiveTimer {
+            timer: { // Correctly assign the block expression to the timer field
+                let mut timer = Timer::new(Duration::from_secs_f32(3.0), TimerMode::Repeating); // Default duration, will be overwritten by stage config
+                timer.pause(); // Start paused
+                timer
+            }
+        })
+        .insert_resource(AttackDiveTimer {
+            timer: {
+                let mut timer = Timer::new(Duration::from_secs_f32(3.0), TimerMode::Repeating);
+                timer.pause(); // Start paused
+                timer
+            },
+        })
         // Add Systems
         .add_systems(Startup, setup)
         // Systems running only when Playing
-        .add_systems(Update, (
-            move_player,
-            player_shoot.run_if(player_exists),
-            move_bullets,
-            move_enemies,
-            spawn_enemies,
-            check_bullet_collisions,
-            check_player_enemy_collisions.run_if(player_vulnerable),
-            respawn_player.run_if(should_respawn_player),
-            manage_invincibility,
-            // Game Over check is now implicit in check_player_enemy_collisions
-        ).run_if(in_state(AppState::Playing)))
+        .add_systems(
+            Update,
+            (
+                // Player systems
+                move_player,
+                player_shoot.run_if(player_exists),
+                check_player_enemy_collisions.run_if(player_vulnerable),
+                respawn_player.run_if(should_respawn_player),
+                manage_invincibility,
+                // Bullet systems
+                move_bullets,
+                check_bullet_collisions,
+                move_enemy_bullets,
+                check_enemy_bullet_player_collisions.run_if(player_vulnerable),
+                // Enemy systems
+                spawn_enemies,
+                move_enemies,
+                enemy_shoot, // Consider run_if attacking state? (Handled internally for now)
+            )
+                .run_if(in_state(AppState::Playing)),
+        )
+        // Formation/Attack/Stage systems (some need specific ordering or run conditions)
+        .add_systems(
+            Update,
+            (
+                check_formation_complete,
+                trigger_attack_dives.run_if(is_formation_complete), // Run only when formation is complete
+                check_stage_clear, // Uses world access, run separately
+            )
+                .chain() // Ensure these run in order if needed, check_formation first
+                .run_if(in_state(AppState::Playing)),
+        )
         // Systems running regardless of state (or managing state transitions)
-        .add_systems(Update, (
-            update_window_title, // Keep title updated
-            // Add system to check for restart input in GameOver state later
-            bevy::window::close_on_esc, // Allow closing anytime
-        ))
+        .add_systems(
+            Update,
+            (
+                update_window_title, // Keep title updated
+                // TODO: Add system to check for restart input in GameOver state
+                bevy::window::close_on_esc, // Allow closing anytime
+            ),
+        )
         // Systems for entering/exiting states
         .add_systems(OnEnter(AppState::GameOver), setup_game_over_ui)
         .add_systems(OnExit(AppState::GameOver), cleanup_game_over_ui)
         .add_systems(OnExit(AppState::Playing), cleanup_game_entities) // Cleanup when leaving Playing
         .run();
 }
-
-// --- Run Conditions ---
-fn player_exists(query: Query<&Player>) -> bool {
-    !query.is_empty()
-}
-
-fn player_vulnerable(query: Query<&Player, Without<Invincible>>) -> bool {
-    !query.is_empty()
-}
-
-fn should_respawn_player(
-    lives: Res<PlayerLives>,
-    player_query: Query<&Player>,
-) -> bool {
-    player_query.is_empty() && lives.count > 0
-}
-
-
-// --- Systems ---
-
-fn setup(mut commands: Commands) {
-    commands.spawn(Camera2dBundle::default());
-    spawn_player_ship(&mut commands); // Use helper function
-}
-
-// Helper to spawn player (used in setup and respawn)
-fn spawn_player_ship(commands: &mut Commands) {
-     commands.spawn((
-        SpriteBundle {
-            sprite: Sprite {
-                color: Color::rgb(0.0, 0.5, 1.0),
-                custom_size: Some(PLAYER_SIZE),
-                ..default()
-            },
-            transform: Transform::from_translation(Vec3::new(0.0, -WINDOW_HEIGHT / 2.0 + PLAYER_SIZE.y / 2.0 + 20.0, 0.0)),
-            ..default()
-        },
-        Player {
-            speed: PLAYER_SPEED,
-            shoot_cooldown: Timer::new(Duration::from_secs_f32(0.3), TimerMode::Once),
-        },
-        // Player starts invincible for a short time
-        Invincible {
-            timer: Timer::new(Duration::from_secs_f32(PLAYER_INVINCIBILITY_DURATION), TimerMode::Once)
-        }
-    ));
-    println!("Player spawned!");
-}
-
-
-fn move_player(
-    keyboard_input: Res<ButtonInput<KeyCode>>,
-    mut query: Query<(&mut Transform, &Player)>,
-    time: Res<Time>,
-) {
-    // Using get_single_mut handles the case where player might not exist yet (or was just destroyed)
-    if let Ok((mut transform, player)) = query.get_single_mut() {
-        let mut direction = 0.0;
-
-        if keyboard_input.pressed(KeyCode::KeyA) || keyboard_input.pressed(KeyCode::ArrowLeft) {
-            direction -= 1.0;
-        }
-
-        if keyboard_input.pressed(KeyCode::KeyD) || keyboard_input.pressed(KeyCode::ArrowRight) {
-            direction += 1.0;
-        }
-
-        transform.translation.x += direction * player.speed * time.delta_seconds();
-        let half_player_width = PLAYER_SIZE.x / 2.0;
-        transform.translation.x = transform.translation.x.clamp(-WINDOW_WIDTH / 2.0 + half_player_width, WINDOW_WIDTH / 2.0 - half_player_width);
-    }
-}
-
-fn player_shoot(
-    keyboard_input: Res<ButtonInput<KeyCode>>,
-    mut query: Query<(&Transform, &mut Player)>, // Should only run if player exists due to run_if
-    mut commands: Commands,
-    time: Res<Time>,
-) {
-   if let Ok((player_transform, mut player)) = query.get_single_mut() {
-        player.shoot_cooldown.tick(time.delta());
-
-        if (keyboard_input.just_pressed(KeyCode::Space) || keyboard_input.just_pressed(KeyCode::ArrowUp))
-            && player.shoot_cooldown.finished() {
-            player.shoot_cooldown.reset();
-
-            let bullet_start_pos = player_transform.translation + Vec3::Y * (PLAYER_SIZE.y / 2.0 + BULLET_SIZE.y / 2.0);
-
-            commands.spawn((
-                SpriteBundle {
-                    sprite: Sprite {
-                        color: Color::rgb(1.0, 1.0, 1.0),
-                        custom_size: Some(BULLET_SIZE),
-                        ..default()
-                    },
-                    transform: Transform::from_translation(bullet_start_pos),
-                    ..default()
-                },
-                Bullet,
-            ));
-        }
-    }
-}
-
-fn move_bullets(
-    mut query: Query<(Entity, &mut Transform), With<Bullet>>,
-    time: Res<Time>,
-    mut commands: Commands,
-) {
-    for (entity, mut transform) in query.iter_mut() {
-        transform.translation.y += BULLET_SPEED * time.delta_seconds();
-
-        if transform.translation.y > WINDOW_HEIGHT / 2.0 + BULLET_SIZE.y {
-            commands.entity(entity).despawn();
-        }
-    }
-}
-
-fn spawn_enemies(
-    mut commands: Commands,
-    time: Res<Time>,
-    mut timer: ResMut<EnemySpawnTimer>,
-) {
-    timer.timer.tick(time.delta());
-
-    if timer.timer.just_finished() {
-        let x_pos = (fastrand::f32() - 0.5) * (WINDOW_WIDTH - ENEMY_SIZE.x);
-
-        commands.spawn((
-            SpriteBundle {
-                sprite: Sprite {
-                    color: Color::rgb(1.0, 0.2, 0.2),
-                    custom_size: Some(ENEMY_SIZE),
-                    ..default()
-                },
-                transform: Transform::from_translation(Vec3::new(
-                    x_pos,
-                    WINDOW_HEIGHT / 2.0 - ENEMY_SIZE.y / 2.0,
-                    0.0
-                )),
-                ..default()
-            },
-            Enemy,
-        ));
-    }
-}
-
-fn move_enemies(
-    mut query: Query<(Entity, &mut Transform), With<Enemy>>,
-    time: Res<Time>,
-    mut commands: Commands,
-) {
-    for (entity, mut transform) in query.iter_mut() {
-        transform.translation.y -= ENEMY_SPEED * time.delta_seconds();
-
-        if transform.translation.y < -WINDOW_HEIGHT / 2.0 - ENEMY_SIZE.y {
-            commands.entity(entity).despawn();
-        }
-    }
-}
-
-fn check_bullet_collisions(
-    mut commands: Commands,
-    bullet_query: Query<(Entity, &Transform), With<Bullet>>,
-    enemy_query: Query<(Entity, &Transform), With<Enemy>>,
-) {
-    for (bullet_entity, bullet_transform) in bullet_query.iter() {
-        for (enemy_entity, enemy_transform) in enemy_query.iter() {
-            let distance = bullet_transform.translation.distance(enemy_transform.translation);
-
-            if distance < BULLET_ENEMY_COLLISION_THRESHOLD {
-                commands.entity(bullet_entity).despawn();
-                commands.entity(enemy_entity).despawn();
-                break;
-            }
-        }
-    }
-}
-
-// Modified Collision Check for Player
-fn check_player_enemy_collisions(
-    mut commands: Commands,
-    mut lives: ResMut<PlayerLives>,
-    mut respawn_timer: ResMut<PlayerRespawnTimer>,
-    mut next_state: ResMut<NextState<AppState>>, // Resource to change state
-    // Query player without Invincible component - relies on run_if condition too
-    player_query: Query<(Entity, &Transform), (With<Player>, Without<Invincible>)>, 
-    enemy_query: Query<(Entity, &Transform), With<Enemy>>,
-) {
-    // This system only runs if player exists and is not invincible, due to run_if
-    if let Ok((player_entity, player_transform)) = player_query.get_single() {
-        for (enemy_entity, enemy_transform) in enemy_query.iter() {
-            let distance = player_transform.translation.distance(enemy_transform.translation);
-
-            if distance < PLAYER_ENEMY_COLLISION_THRESHOLD {
-                println!("Player hit!");
-                commands.entity(enemy_entity).despawn(); // Despawn enemy
-
-                lives.count = lives.count.saturating_sub(1); // Decrement lives safely
-                println!("Lives remaining: {}", lives.count);
-
-                commands.entity(player_entity).despawn(); // Despawn player
-
-                if lives.count > 0 {
-                    // Start the respawn timer
-                    respawn_timer.timer.reset();
-                    respawn_timer.timer.unpause();
-                    println!("Respawn timer started.");
-                } else {
-                    println!("GAME OVER!");
-                    next_state.set(AppState::GameOver); // Transition to GameOver state
-                }
-                // Important: Break after handling one collision per frame for the player
-                break;
-            }
-        }
-    }
-}
-
-// New System: Respawn Player
-fn respawn_player(
-    mut commands: Commands,
-    time: Res<Time>,
-    mut respawn_timer: ResMut<PlayerRespawnTimer>,
-    // No player query needed here due to run_if condition
-) {
-    // Tick the timer only if it's actually running
-    if respawn_timer.timer.tick(time.delta()).just_finished() {
-         println!("Respawn timer finished. Spawning player.");
-         spawn_player_ship(&mut commands);
-         respawn_timer.timer.pause(); // Pause timer until next death
-    }
-}
-
-// New System: Manage Invincibility
-fn manage_invincibility(
-    mut commands: Commands,
-    time: Res<Time>,
-    mut query: Query<(Entity, &mut Invincible, Option<&mut Visibility>), With<Player>>,
-) {
-    for (entity, mut invincible, mut visibility) in query.iter_mut() {
-        invincible.timer.tick(time.delta());
-
-        // Blinking effect (optional)
-        if let Some(ref mut vis) = visibility {
-             // Blink roughly 5 times per second
-            let elapsed_secs = invincible.timer.elapsed_secs();
-            **vis = if (elapsed_secs * 10.0).floor() % 2.0 == 0.0 {
-                Visibility::Visible
-            } else {
-                Visibility::Hidden
-            };
-        } 
-        
-
-        if invincible.timer.finished() {
-            println!("Invincibility finished.");
-            commands.entity(entity).remove::<Invincible>();
-             // Ensure player is visible when invincibility ends
-             if let Some(ref mut vis) = visibility {
-                  **vis = Visibility::Visible;
-            }
-        }
-    }
-}
-
-// New System: Update Window Title with Lives
-fn update_window_title(
-    lives: Res<PlayerLives>,
-    mut windows: Query<&mut Window>,
-) {
-    if lives.is_changed() {
-        let mut window = windows.single_mut();
-        window.title = format!("Galaga :: Lives: {}", lives.count);
-    }
-}
diff --git a/src/player.rs b/src/player.rs
new file mode 100644
index 0000000..3554e8a
--- /dev/null
+++ b/src/player.rs
@@ -0,0 +1,189 @@
+use bevy::prelude::*;
+use std::time::Duration;
+
+use crate::components::{Bullet, Enemy, Invincible, Player};
+use crate::constants::{
+    BULLET_SIZE, PLAYER_ENEMY_COLLISION_THRESHOLD, PLAYER_INVINCIBILITY_DURATION, PLAYER_SIZE,
+    PLAYER_SPEED, WINDOW_HEIGHT, WINDOW_WIDTH,
+};
+use crate::game_state::AppState;
+use crate::resources::{PlayerLives, PlayerRespawnTimer};
+
+// Helper to spawn player (used in setup and respawn)
+pub fn spawn_player_ship(commands: &mut Commands) {
+    commands.spawn((
+        SpriteBundle {
+            sprite: Sprite {
+                color: Color::rgb(0.0, 0.5, 1.0),
+                custom_size: Some(PLAYER_SIZE),
+                ..default()
+            },
+            transform: Transform::from_translation(Vec3::new(
+                0.0,
+                -WINDOW_HEIGHT / 2.0 + PLAYER_SIZE.y / 2.0 + 20.0,
+                0.0,
+            )),
+            ..default()
+        },
+        Player {
+            speed: PLAYER_SPEED,
+            shoot_cooldown: Timer::new(Duration::from_secs_f32(0.3), TimerMode::Once),
+        },
+        // Player starts invincible for a short time
+        Invincible {
+            timer: Timer::new(
+                Duration::from_secs_f32(PLAYER_INVINCIBILITY_DURATION),
+                TimerMode::Once,
+            ),
+        },
+    ));
+    println!("Player spawned!");
+}
+
+pub fn move_player(
+    keyboard_input: Res<ButtonInput<KeyCode>>,
+    mut query: Query<(&mut Transform, &Player)>,
+    time: Res<Time>,
+) {
+    // Using get_single_mut handles the case where player might not exist yet (or was just destroyed)
+    if let Ok((mut transform, player)) = query.get_single_mut() {
+        let mut direction = 0.0;
+
+        if keyboard_input.pressed(KeyCode::KeyA) || keyboard_input.pressed(KeyCode::ArrowLeft) {
+            direction -= 1.0;
+        }
+
+        if keyboard_input.pressed(KeyCode::KeyD) || keyboard_input.pressed(KeyCode::ArrowRight) {
+            direction += 1.0;
+        }
+
+        transform.translation.x += direction * player.speed * time.delta_seconds();
+        let half_player_width = PLAYER_SIZE.x / 2.0;
+        transform.translation.x = transform.translation.x.clamp(
+            -WINDOW_WIDTH / 2.0 + half_player_width,
+            WINDOW_WIDTH / 2.0 - half_player_width,
+        );
+    }
+}
+
+pub fn player_shoot(
+    keyboard_input: Res<ButtonInput<KeyCode>>,
+    mut query: Query<(&Transform, &mut Player)>, // Should only run if player exists due to run_if
+    mut commands: Commands,
+    time: Res<Time>,
+) {
+    if let Ok((player_transform, mut player)) = query.get_single_mut() {
+        player.shoot_cooldown.tick(time.delta());
+
+        if (keyboard_input.just_pressed(KeyCode::Space)
+            || keyboard_input.just_pressed(KeyCode::ArrowUp))
+            && player.shoot_cooldown.finished()
+        {
+            player.shoot_cooldown.reset();
+
+            let bullet_start_pos = player_transform.translation
+                + Vec3::Y * (PLAYER_SIZE.y / 2.0 + BULLET_SIZE.y / 2.0);
+
+            commands.spawn((
+                SpriteBundle {
+                    sprite: Sprite {
+                        color: Color::rgb(1.0, 1.0, 1.0),
+                        custom_size: Some(BULLET_SIZE),
+                        ..default()
+                    },
+                    transform: Transform::from_translation(bullet_start_pos),
+                    ..default()
+                },
+                Bullet,
+            ));
+        }
+    }
+}
+
+// Modified Collision Check for Player vs Enemy
+pub fn check_player_enemy_collisions(
+    mut commands: Commands,
+    mut lives: ResMut<PlayerLives>,
+    mut respawn_timer: ResMut<PlayerRespawnTimer>,
+    mut next_state: ResMut<NextState<AppState>>, // Resource to change state
+    // Query player without Invincible component - relies on run_if condition too
+    player_query: Query<(Entity, &Transform), (With<Player>, Without<Invincible>)>,
+    enemy_query: Query<(Entity, &Transform), With<Enemy>>,
+) {
+    // This system only runs if player exists and is not invincible, due to run_if
+    if let Ok((player_entity, player_transform)) = player_query.get_single() {
+        for (enemy_entity, enemy_transform) in enemy_query.iter() {
+            let distance = player_transform
+                .translation
+                .distance(enemy_transform.translation);
+
+            if distance < PLAYER_ENEMY_COLLISION_THRESHOLD {
+                println!("Player hit by enemy!");
+                commands.entity(enemy_entity).despawn(); // Despawn enemy
+
+                lives.count = lives.count.saturating_sub(1); // Decrement lives safely
+                println!("Lives remaining: {}", lives.count);
+
+                commands.entity(player_entity).despawn(); // Despawn player
+
+                if lives.count > 0 {
+                    // Start the respawn timer
+                    respawn_timer.timer.reset();
+                    respawn_timer.timer.unpause();
+                    println!("Respawn timer started.");
+                } else {
+                    println!("GAME OVER!");
+                    next_state.set(AppState::GameOver); // Transition to GameOver state
+                }
+                // Important: Break after handling one collision per frame for the player
+                break;
+            }
+        }
+    }
+}
+
+// New System: Respawn Player
+pub fn respawn_player(
+    mut commands: Commands,
+    time: Res<Time>,
+    mut respawn_timer: ResMut<PlayerRespawnTimer>,
+    // No player query needed here due to run_if condition
+) {
+    // Tick the timer only if it's actually running
+    if respawn_timer.timer.tick(time.delta()).just_finished() {
+        println!("Respawn timer finished. Spawning player.");
+        spawn_player_ship(&mut commands);
+        respawn_timer.timer.pause(); // Pause timer until next death
+    }
+}
+
+// New System: Manage Invincibility
+pub fn manage_invincibility(
+    mut commands: Commands,
+    time: Res<Time>,
+    mut query: Query<(Entity, &mut Invincible, Option<&mut Visibility>), With<Player>>,
+) {
+    for (entity, mut invincible, mut visibility) in query.iter_mut() {
+        invincible.timer.tick(time.delta());
+
+        // Blinking effect (optional)
+        if let Some(ref mut vis) = visibility {
+            // Blink roughly 5 times per second
+            let elapsed_secs = invincible.timer.elapsed_secs();
+            **vis = if (elapsed_secs * 10.0).floor() % 2.0 == 0.0 {
+                Visibility::Visible
+            } else {
+                Visibility::Hidden
+            };
+        }
+
+        if invincible.timer.finished() {
+            println!("Invincibility finished.");
+            commands.entity(entity).remove::<Invincible>();
+            // Ensure player is visible when invincibility ends
+            if let Some(ref mut vis) = visibility {
+                **vis = Visibility::Visible;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/resources.rs b/src/resources.rs
new file mode 100644
index 0000000..7a21d4e
--- /dev/null
+++ b/src/resources.rs
@@ -0,0 +1,126 @@
+use bevy::prelude::*;
+use std::time::Duration; // Needed for Timer
+
+// --- Resources ---
+#[derive(Resource)]
+pub struct EnemySpawnTimer {
+    pub timer: Timer,
+}
+
+#[derive(Resource)]
+pub struct PlayerLives {
+    pub count: u32,
+}
+
+#[derive(Resource)]
+pub struct PlayerRespawnTimer {
+    pub timer: Timer,
+}
+
+// New struct to define formation positions
+#[derive(Clone, Debug)]
+pub struct FormationLayout {
+    pub name: String, // Optional name for debugging/identification
+    pub positions: Vec<Vec3>,
+}
+
+// Default implementation for easy initialization
+impl Default for FormationLayout {
+    fn default() -> Self {
+        // Default to the original grid formation for now
+        let mut positions = Vec::with_capacity(crate::constants::FORMATION_ENEMY_COUNT);
+        for i in 0..crate::constants::FORMATION_ENEMY_COUNT {
+            let row = i / crate::constants::FORMATION_COLS;
+            let col = i % crate::constants::FORMATION_COLS;
+            let target_x = (col as f32 - (crate::constants::FORMATION_COLS as f32 - 1.0) / 2.0) * crate::constants::FORMATION_X_SPACING;
+            let target_y = crate::constants::FORMATION_BASE_Y - (row as f32 * crate::constants::FORMATION_Y_SPACING);
+            positions.push(Vec3::new(target_x, target_y, 0.0));
+        }
+        FormationLayout {
+            name: "Default Grid".to_string(),
+            positions,
+        }
+    }
+}
+
+// Configuration for a single stage
+#[derive(Clone, Debug)]
+pub struct StageConfig {
+    pub formation_layout: FormationLayout,
+    pub enemy_count: usize, // Allow overriding enemy count per stage
+    pub attack_patterns: Vec<crate::components::AttackPattern>, // Possible patterns for this stage
+    pub attack_dive_interval: f32, // Time between attack dives for this stage
+    pub enemy_speed_multiplier: f32, // Speed multiplier for this stage
+    pub enemy_shoot_interval: f32, // Shoot interval for this stage
+}
+
+// Resource to hold all stage configurations
+#[derive(Resource, Debug, Clone)]
+pub struct StageConfigurations {
+    pub stages: Vec<StageConfig>,
+}
+
+impl Default for StageConfigurations {
+    fn default() -> Self {
+        use crate::components::AttackPattern;
+        use crate::constants::*; // Import constants for default values
+
+        // Define configurations for a few stages
+        let stage1 = StageConfig {
+            formation_layout: FormationLayout::default(), // Use the default grid
+            enemy_count: FORMATION_ENEMY_COUNT,
+            attack_patterns: vec![AttackPattern::SwoopDive],
+            attack_dive_interval: 3.0,
+            enemy_speed_multiplier: 1.0,
+            enemy_shoot_interval: ENEMY_SHOOT_INTERVAL,
+        };
+
+        let stage2_layout = {
+            let mut positions = Vec::new();
+            let radius = WINDOW_WIDTH / 4.0;
+            let center_y = FORMATION_BASE_Y - 50.0;
+            let count = 16; // Example: Fewer enemies in a circle
+            for i in 0..count {
+                let angle = (i as f32 / count as f32) * 2.0 * std::f32::consts::PI;
+                positions.push(Vec3::new(angle.cos() * radius, center_y + angle.sin() * radius, 0.0));
+            }
+            FormationLayout { name: "Circle".to_string(), positions }
+        };
+        let stage2 = StageConfig {
+            formation_layout: stage2_layout,
+            enemy_count: 16,
+            attack_patterns: vec![AttackPattern::SwoopDive, AttackPattern::DirectDive], // Add direct dive
+            attack_dive_interval: 2.5, // Faster dives
+            enemy_speed_multiplier: 1.2, // Faster enemies
+            enemy_shoot_interval: ENEMY_SHOOT_INTERVAL * 0.8, // Faster shooting
+        };
+
+        // Add more stages here...
+
+        StageConfigurations {
+            stages: vec![stage1, stage2], // Add more stages as needed
+        }
+    }
+}
+#[derive(Resource)]
+pub struct Score {
+    pub value: u32,
+}
+
+#[derive(Resource)]
+pub struct CurrentStage {
+    pub number: u32,
+    pub waiting_for_clear: bool, // Flag to check if we should check for stage clear
+}
+
+#[derive(Resource)]
+pub struct FormationState {
+    pub next_slot_index: usize,
+    pub total_spawned_this_stage: usize,
+    pub formation_complete: bool, // Flag to indicate if all enemies are in position
+}
+
+#[derive(Resource)]
+pub struct AttackDiveTimer {
+    pub timer: Timer,
+}
\ No newline at end of file
diff --git a/src/stage.rs b/src/stage.rs
new file mode 100644
index 0000000..1c56969
--- /dev/null
+++ b/src/stage.rs
@@ -0,0 +1,37 @@
+use bevy::prelude::*;
+
+use crate::components::Enemy;
+use crate::resources::{CurrentStage, EnemySpawnTimer, FormationState};
+
+// Helper to access world directly in check_stage_clear
+pub fn check_stage_clear(world: &mut World) {
+    // Use manual resource access because we need mutable access to multiple resources
+    // Separate checks to manage borrows correctly
+    let mut should_clear = false;
+    if let Some(stage) = world.get_resource::<CurrentStage>() {
+        if stage.waiting_for_clear {
+            // Create the query *after* checking the flag
+            let mut enemy_query = world.query_filtered::<Entity, With<Enemy>>();
+            if enemy_query.iter(world).next().is_none() {
+                should_clear = true;
+            }
+        }
+    }
+
+    if should_clear {
+        // Get mutable resources only when needed
+        if let Some(mut stage) = world.get_resource_mut::<CurrentStage>() {
+            stage.number += 1;
+            stage.waiting_for_clear = false;
+            println!("Stage cleared! Starting Stage {}...", stage.number);
+        }
+        if let Some(mut formation_state) = world.get_resource_mut::<FormationState>() {
+            formation_state.next_slot_index = 0;
+            formation_state.total_spawned_this_stage = 0;
+            formation_state.formation_complete = false; // Reset flag for new stage
+        }
+        if let Some(mut spawn_timer) = world.get_resource_mut::<EnemySpawnTimer>() {
+            spawn_timer.timer.reset();
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/systems.rs b/src/systems.rs
new file mode 100644
index 0000000..ce23cb1
--- /dev/null
+++ b/src/systems.rs
@@ -0,0 +1,45 @@
+use bevy::prelude::*;
+
+use crate::components::{Invincible, Player};
+use crate::resources::{CurrentStage, FormationState, PlayerLives, Score};
+use crate::player::spawn_player_ship; // Import the helper function
+
+// --- Setup ---
+pub fn setup(mut commands: Commands) {
+    commands.spawn(Camera2dBundle::default());
+    spawn_player_ship(&mut commands); // Use helper function from player module
+}
+
+// --- Run Conditions ---
+pub fn player_exists(query: Query<&Player>) -> bool {
+    !query.is_empty()
+}
+
+pub fn player_vulnerable(query: Query<&Player, Without<Invincible>>) -> bool {
+    !query.is_empty()
+}
+
+pub fn should_respawn_player(lives: Res<PlayerLives>, player_query: Query<&Player>) -> bool {
+    player_query.is_empty() && lives.count > 0
+}
+
+// Moved is_formation_complete to enemy.rs as it's closely related to enemy logic
+
+// --- General Systems ---
+
+// Update Window Title with Lives, Score, and Stage
+pub fn update_window_title(
+    lives: Res<PlayerLives>,
+    score: Res<Score>,
+    stage: Res<CurrentStage>, // Add CurrentStage resource
+    mut windows: Query<&mut Window>,
+) {
+    // Update if lives, score, or stage changed
+    if lives.is_changed() || score.is_changed() || stage.is_changed() {
+        let mut window = windows.single_mut();
+        window.title = format!(
+            "Galaga :: Stage: {} Lives: {} Score: {}",
+            stage.number, lives.count, score.value
+        );
+    }
+}
\ No newline at end of file