Add grid-based death pulse visual effect for enemies

js/entities/enemies/BaseEnemy.js

@@ -1,6 +1,7 @@
 const HP_BAR_WIDTH = 30;
 const HP_BAR_HEIGHT = 4;
 const HP_BAR_OFFSET_Y = -30;
+const GRID = 80;
 
 export class BaseEnemy {
   constructor(scene, x, y, player, config) {
@@ -120,6 +121,36 @@ export class BaseEnemy {
     this._checkContact(delta);
   }
 
+  _gridDeathPulse() {
+    if (!this._deathPulseColor || !this.scene._pulseEffects) return;
+    const scene = this.scene;
+    const W = scene.scale.width;
+    const H = scene.scale.height;
+    const col = Math.floor(this.x / GRID);
+    const row = Math.floor(this.y / GRID);
+    const color = this._deathPulseColor;
+
+    const makeTile = (c, r, alpha) => {
+      if (c < 0 || r < 0 || c * GRID >= W || r * GRID >= H) return null;
+      return scene.add.rectangle(
+        c * GRID + GRID / 2, r * GRID + GRID / 2,
+        GRID, GRID, color, alpha,
+      ).setDepth(2);
+    };
+
+    const center = makeTile(col, row, 0.55);
+    const adjacents = [];
+    [[-1, 0], [1, 0], [0, -1], [0, 1]].forEach(([dc, dr]) => {
+      const t = makeTile(col + dc, row + dr, 0.38);
+      if (t) { t.setVisible(false); adjacents.push(t); }
+    });
+
+    scene._pulseEffects.push({
+      center, adjacents, elapsed: 0, adjSpawned: false,
+      ADJ_MS: 80, FADE_MS: 120, END_MS: 400,
+    });
+  }
+
   destroy() {
     this.sprite?.destroy();
     this._hpBg?.destroy();

js/entities/enemies/ChaseEnemy.js

@@ -1,5 +1,7 @@
 import { BaseEnemy } from './BaseEnemy.js';
 
+const GRID = 80;
+
 export class ChaseEnemy extends BaseEnemy {
   constructor(scene, x, y, player) {
     super(scene, x, y, player, {
@@ -20,4 +22,45 @@ export class ChaseEnemy extends BaseEnemy {
       Math.sin(angle) * this.speed
     );
   }
+
+  _die() {
+    this._gridDeathPulse(this.x, this.y);
+    super._die();
+  }
+
+  _gridDeathPulse(px, py) {
+    const scene = this.scene;
+    const W = scene.scale.width;
+    const H = scene.scale.height;
+    const col = Math.floor(px / GRID);
+    const row = Math.floor(py / GRID);
+
+    const makeTile = (c, r, alpha) => {
+      if (c < 0 || r < 0 || c * GRID >= W || r * GRID >= H) return null;
+      return scene.add.rectangle(
+        c * GRID + GRID / 2,
+        r * GRID + GRID / 2,
+        GRID, GRID, 0x00ff44, alpha,
+      ).setDepth(2);
+    };
+
+    const center = makeTile(col, row, 0.55);
+
+    // Pre-create adjacent tiles but hide them until ADJ_MS elapses
+    const adjacents = [];
+    [[-1, 0], [1, 0], [0, -1], [0, 1]].forEach(([dc, dr]) => {
+      const t = makeTile(col + dc, row + dr, 0.38);
+      if (t) { t.setVisible(false); adjacents.push(t); }
+    });
+
+    scene._pulseEffects.push({
+      center,
+      adjacents,
+      elapsed:    0,
+      adjSpawned: false,
+      ADJ_MS:  80,
+      FADE_MS: 120,
+      END_MS:  400,
+    });
+  }
 }

js/scenes/GameScene.js

@@ -53,6 +53,7 @@ export class GameScene extends Phaser.Scene {
     this._levelUpPending = false;
     this._frozen = false;
     this._waitingForExit = false;
+    this._pulseEffects = [];
 
     this.events.on('zone-waves-complete', () => this._startZoneExit());
 
@@ -117,10 +118,35 @@ export class GameScene extends Phaser.Scene {
     this._checkBulletHits();
     this._checkEnemyProjectileHits();
     this._pruneEnemyProjectiles();
+    this._updatePulseEffects(delta);
 
     if (this._waitingForExit) this._checkPlayerExit();
   }
 
+  _updatePulseEffects(delta) {
+    this._pulseEffects = this._pulseEffects.filter(effect => {
+      effect.elapsed += delta;
+
+      if (!effect.adjSpawned && effect.elapsed >= effect.ADJ_MS) {
+        effect.adjSpawned = true;
+        effect.adjacents.forEach(t => { if (t?.active) t.setVisible(true); });
+      }
+
+      if (effect.elapsed >= effect.FADE_MS) {
+        const progress = Math.min(1, (effect.elapsed - effect.FADE_MS) / (effect.END_MS - effect.FADE_MS));
+        if (effect.center?.active) effect.center.alpha = Math.max(0, 0.55 * (1 - progress));
+        effect.adjacents.forEach(t => { if (t?.active) t.alpha = Math.max(0, 0.38 * (1 - progress)); });
+      }
+
+      if (effect.elapsed >= effect.END_MS) {
+        if (effect.center?.active) effect.center.destroy();
+        effect.adjacents.forEach(t => { if (t?.active) t.destroy(); });
+        return false; // remove from array
+      }
+      return true;
+    });
+  }
+
   _checkBulletHits() {
     const bullets = this.player.bullets.getChildren();
     const enemies = this.waveManager.enemies;
@@ -339,5 +365,6 @@ export class GameScene extends Phaser.Scene {
     this.waveManager?.reset();
     this.hud?.destroy();
     this._enemyProjectiles = [];
+    this._pulseEffects = [];
   }
 }