Duke Nukem: Zero Hour

Duke is called into action by the government as aliens have once again landed and are wreaking havoc. Duke battles the alien menace through the streets of New York with the help of some Marines and eventually gains access to the Statue of Liberty . There, Duke uncovers the aliens' true plan: to travel back in time and alter historical events, ensuring Earth becomes a world they can easily conquer. However, during the fight, Duke is teleported to the future, where the aliens have won, and humans are on the brink of extinction.

In this future, Duke battles new alien breeds and the zombified corpses of those who didn’t survive the fallout. S. Army headquarters in New York. The resistance informs Duke that the aliens are tampering with history, creating alternate futures.

To restore the original timeline, Duke must fight back. The humans have developed a time machine to send a soldier back to rewrite history and destroy the aliens. Duke is sent to the Old West, where the aliens have taken control of parts of the American frontier and plan to detonate a bomb in Earth's core, threatening to destroy the planet. In the Old West, Duke faces technical difficulties that force him to rely mostly on period-appropriate weapons, although a few of his modern weapons are sent back by his allies.

The aliens have begun creating super-soldiers to fight both Duke and the humans of the future. After destroying a ship carrying the super-soldiers, Duke heads to Roswell, where he prevents the aliens from detonating the bomb. Duke is then informed that the aliens are not only altering America's past but have also traveled to the Victorian Era in London. In Victorian London, Duke faces the alien-created biological weapons.

Zombies roam the streets, and Brains float in the air. Duke defeats a mini-boss, the infamous Jack the Ripper . Duke fights his way toward a castle that the aliens have seized, blowing up a Zeppelin along the way. Inside the castle, he confronts the most horrific of the aliens' creations and finally faces off against the alien general—a giant brain.

After destroying the castle and neutralizing the alien threat in this time period, Duke is ready for some rest and relaxation. Unfortunately, the aliens have caused a rift in the space-time continuum, and now more aliens from various points in history are flooding into New York in a last-ditch effort to wipe out humanity. Duke once again fights through the city streets, eventually entering the alien mothership. He battles wave after wave of enemies, finally confronting the mastermind behind the chaos: Zero.

Using the alien technology aboard the mothership, Duke battles Zero on the rooftops of the city. After defeating the creature, Duke restores the timeline and rids Manhattan of the alien menace.