With the release of "20th Anniversary World Tour", the story progresses further. In "Episode Five: "Alien World Order"", Duke finds out that the aliens initiated a world-scale invasion, so he sets out to repel their attack on various countries. Duke proceeds to clear out aliens from Amsterdam, Moscow, London, San Francisco, Paris, the Giza pyramid complex, and Rome, with the final showdown with the returning alien threat taking place in Los Angeles, taking the game full circle. There, he defeats the Cycloid Incinerator, the current alien leader, stopping their threat for good.