Let us start here, from square one. No, from Zero!

cfg/game.cpp

@@ -0,0 +1,25 @@
+#include "game.h"
+
+/////////////////////////
+/// Private Functions ///
+/////////////////////////
+
+// add button items
+void Game::addItem(Button button) {
+    this->buttons.push_back(std::move(button));
+}
+
+// add analog items
+void Game::addItem(Analog analog) {
+    this->analogs.push_back(std::move(analog));
+}
+
+// add light items
+void Game::addItem(Light light) {
+    this->lights.push_back(std::move(light));
+}
+
+// add option items
+void Game::addItem(Option option) {
+    this->options.push_back(std::move(option));
+}