feat: Implement difficulty scaling for enemy damage and enhance enemy behaviors

- Added `scaleIncomingEnemyDamage` method to `Difficulty` enum for handling damage scaling based on difficulty level.
- Introduced `lives` attribute to `Player` class with methods to manage lives.
- Updated enemy classes (`Dog`, `Guard`, `Mutant`, `Officer`, `SS`, `HansGrosse`) to utilize difficulty settings for health and damage calculations.
- Modified enemy drop logic to reflect new collectible types and behaviors.
- Created tests for verifying enemy drop parity, collectible values, and difficulty damage scaling.
- Adjusted enemy spawn logic to ensure standing enemies remain idle until alerted.
- Enhanced scoring system to reflect updated score values for different enemy types.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_dart/lib/src/engine/player/player.dart

@@ -15,6 +15,7 @@ class Player {
   int health = 100;
   int ammo = 8;
   int score = 0;
+  int lives = 3;
 
   // Damage flash
   double damageFlash = 0.0; // 0.0 is none, 1.0 is maximum red
@@ -135,6 +136,10 @@ class Player {
     ammo = newAmmo;
   }
 
+  void addLives(int amount) {
+    lives = math.min(9, lives + amount);
+  }
+
   /// Attempts to collect [item] and returns the SFX to play.
   ///
   /// Returns `null` when the item was not collected (for example: full health).
@@ -164,6 +169,10 @@ class Player {
       score += effect.scoreToAdd;
     }
 
+    if (effect.extraLivesToAdd > 0) {
+      addLives(effect.extraLivesToAdd);
+    }
+
     if (effect.grantGoldKey) {
       hasGoldKey = true;
     }

packages/wolf_3d_dart/lib/src/engine/wolf_3d_engine_base.dart

@@ -125,6 +125,8 @@ class WolfEngine {
   List<Entity> entities = [];
 
   int _currentEpisodeIndex = 0;
+
+  bool _isPlayerMovingFast = false;
   int _currentLevelIndex = 0;
 
   /// Stores the previous level index when entering a secret floor,
@@ -213,6 +215,10 @@ class WolfEngine {
       inputResult.movement,
     );
 
+    // RUN key does not exist yet in current input model. Keep canonical hit
+    // chance in "walking" mode until true run-state input is implemented.
+    _isPlayerMovingFast = false;
+
     player.x = validatedPos.x;
     player.y = validatedPos.y;
 
@@ -533,9 +539,14 @@ class WolfEngine {
           elapsedMs: _timeAliveMs,
           elapsedDeltaMs: elapsed.inMilliseconds,
           playerPosition: player.position,
+          playerAngle: player.angle,
+          isPlayerRunning: _isPlayerMovingFast,
           isWalkable: isWalkable,
           tryOpenDoor: doorManager.tryOpenDoor,
-          onDamagePlayer: (int damage) => player.takeDamage(damage),
+          onDamagePlayer: (int damage) {
+            final difficultyMode = difficulty ?? Difficulty.medium;
+            player.takeDamage(difficultyMode.scaleIncomingEnemyDamage(damage));
+          },
           onPlaySound: audio.playSoundEffect,
         );
 
@@ -561,14 +572,25 @@ class WolfEngine {
             entity.isDying &&
             !entity.hasDroppedItem) {
           entity.hasDroppedItem = true;
-          Entity? droppedAmmo = EntityRegistry.spawn(
-            MapObject.ammoClip,
-            entity.x,
-            entity.y,
-            difficulty!,
-            data.sprites.length,
-          );
-          if (droppedAmmo != null) itemsToAdd.add(droppedAmmo);
+
+          Entity? droppedItem;
+          if (entity is Dog) {
+            droppedItem = null;
+          } else if (entity is SS) {
+            droppedItem = !player.hasMachineGun
+                ? WeaponCollectible(
+                    x: entity.x,
+                    y: entity.y,
+                    mapId: MapObject.machineGun,
+                  )
+                : SmallAmmoCollectible(x: entity.x, y: entity.y);
+          } else if (entity is Guard || entity is Officer || entity is Mutant) {
+            droppedItem = SmallAmmoCollectible(x: entity.x, y: entity.y);
+          }
+
+          if (droppedItem != null) {
+            itemsToAdd.add(droppedItem);
+          }
         }
       } else if (entity is Collectible) {
         if (player.position.distanceTo(entity.position) < 0.5) {