Added copy operators for game's static instance

Player
CommandParser can be swapped but not copied.

Engine/headers/game.h

@@ -2,6 +2,7 @@
 #include <filesystem>
 #include <fstream>
 #include <string>
+#include <utility>
 #include <vector>
 #include "CommandParser.h"
 #include "game.h"
@@ -37,6 +38,9 @@ private:
 
 public:
     Game();
+    Game(Game& rhs);
+    Game& operator=(Game& rhs);
+
     inline bool GetIsActive() const { return isActive; }
     bool Init();
     void Run();
@@ -54,18 +58,24 @@ public:
 
     void SetIsActive(const bool active) { isActive = active; }
 
-    static void SetGameInstance(Game * g) {
-        game_ = g;
-    }
-
     static Game &Instance() {
         if (game_ == nullptr) {
             game_ = new Game();
+            game_->Init();
         }
         return *game_;
     }
 
-    ~Game() = default;
+    inline friend void swap(Game &lhs, Game &rhs)
+    {
+        using std::swap;
+        swap(lhs.isActive, rhs.isActive);
+        swap(lhs.progress, rhs.progress);
+        swap(lhs.player, rhs.player);
+        swap(lhs.parser, rhs.parser);
+    }
+
+    ~Game();
 };
 
 // Commands