Play the game's SND0.AT3 when a game is selected in the menu and on the "game screen".

UI/BackgroundAudio.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <string>
+
+void SetBackgroundAudioGame(const std::string &path);
+int MixBackgroundAudio(short *buffer, int size);