refactor: get rid of global game variables

src/Common/Game/IGame.cpp

@@ -0,0 +1,26 @@
+#include "IGame.h"
+
+#include "IW3/GameIW3.h"
+#include "IW4/GameIW4.h"
+#include "IW5/GameIW5.h"
+#include "T5/GameT5.h"
+#include "T6/GameT6.h"
+
+#include <cassert>
+
+IGame* IGame::GetGameById(GameId gameId)
+{
+    static IGame* games[static_cast<unsigned>(GameId::COUNT)]{
+        new IW3::Game(),
+        new IW4::Game(),
+        new IW5::Game(),
+        new T5::Game(),
+        new T6::Game(),
+    };
+
+    assert(static_cast<unsigned>(gameId) < static_cast<unsigned>(GameId::COUNT));
+    auto* result = games[static_cast<unsigned>(gameId)];
+    assert(result);
+
+    return result;
+}