Refactor NPC spawning logic and adjust grid size; remove unused power-up type

Assets/Scripts/Core/Domain/GameSession.cs

@@ -1,13 +1,14 @@
 using System;
 using System.Collections.Generic;
 using Core.Ports;
+using UnityEngine;
+using Random = System.Random;
 
 namespace Core.Domain
 {
     public class GameSession
     {
         private const string HighScoreKey = "HighScore";
-        private const float NpcSpawnTime = 30f;
         private const float PowerUpSpawnInterval = 25f;
 
         public int Score { get; private set; }
@@ -15,6 +16,7 @@ namespace Core.Domain
         public bool IsGameOver { get; private set; }
 
         public float TimeDilation { get; private set; } = 1.0f;
+        public float NpcSpawnTime { get; private set; } = 30f;
 
         public event Action<int> OnScoreChanged;
         public event Action<string> OnOrbSpawned;
@@ -28,7 +30,7 @@ namespace Core.Domain
         private readonly Random _rng = new();
         private int _playerFloorIndex = 0;
         private float _timeSinceStart;
-        private bool _npcSpawned;
+        private float _npcTimer;
         private float _powerUpTimer;
 
         private float _timeSlowTimer;
@@ -53,7 +55,6 @@ namespace Core.Domain
         {
             _timeSinceStart = 0f;
             _powerUpTimer = 0f;
-            _npcSpawned = false;
             TimeDilation = 1.0f;
 
             ComboMultiplier = 1;
@@ -67,10 +68,13 @@ namespace Core.Domain
             if (IsGameOver) return;
 
             _timeSinceStart += deltaTime;
-            if (!_npcSpawned && _timeSinceStart >= NpcSpawnTime)
+            _npcTimer += deltaTime;
+            
+            if (_npcTimer >= NpcSpawnTime)
             {
-                _npcSpawned = true;
+                _npcTimer = 0f;
                 OnSpawnNpc?.Invoke();
+                NpcSpawnTime = Mathf.Max(5f, NpcSpawnTime * 0.95f);
             }
 
             _powerUpTimer += deltaTime;
@@ -189,7 +193,6 @@ namespace Core.Domain
             {
                 case 0: type = PowerUpType.LightFooted; break;
                 case 1: type = PowerUpType.SpeedBoost; break;
-                case 2: type = PowerUpType.Hover; break;
                 case 3: type = PowerUpType.TimeSlow; break;
             }