Added GameState controller

Assets/Scripts/GameStateController.cs

@@ -0,0 +1,41 @@
+using PashaBibko.Pacore.Attributes;
+using UnityEngine;
+
+namespace Fruitomation
+{
+    public enum GameState
+    {
+        Simulation,
+        Building,
+        UpgradeMenu,
+        Paused,
+        None
+    }
+
+    [CreateInstanceOnStart] public class GameStateController : MonoBehaviour
+    {
+        private static GameStateController Instance;
+
+        private GameState InternalState = GameState.None;
+        public static GameState State
+        {
+            get => Instance.InternalState;
+            set
+            {
+                Debug.Log($"Changing state from [{Instance.InternalState}] to [{value}]");
+                Instance.InternalState = value;
+            }
+        }
+
+        private void Awake()
+        {
+            if (Instance is not null)
+            {
+                Debug.LogError($"Cannot have multiple instances of [GameStateController]");
+                return;
+            }
+
+            Instance = this;
+        }
+    }
+}