Add initial implementation of game mechanics and resources management

Scripts/Core/GameState.cs

@@ -0,0 +1,27 @@
+using System.Collections.Generic;
+using ParasiticGod.Scripts.Core.Effects;
+
+namespace ParasiticGod.Scripts.Core;
+
+public class GameState
+{
+    public double Faith { get; set; } = 50.0;
+    public double FaithPerFollower { get; set; } = 0.5;
+    public long Followers { get; set; } = 40;
+    public double Corruption { get; set; } = 0.0;
+
+    public List<Buff> ActiveBuffs { get; } = [];
+
+    public double FaithPerSecond
+    {
+        get
+        {
+            var totalMultiplier = 1.0;
+            foreach (var buff in ActiveBuffs)
+            {
+                totalMultiplier *= buff.Multiplier;
+            }
+            return Followers * FaithPerFollower * totalMultiplier;
+        }
+    }
+}