The plot of Half-Life 2 was originally vastly different to the finished product. The beginning of the game was very similar to the beginning of the original, the train ride far longer and showing large glimpses of the Wasteland, City 17, invasive Xen wildlife and Cremators. The Combine still had a human military, one of whom was a member of the resistance who himself was Alyx's father. Eli Vance was a hermit living in a cave that showed Gordon a slideshow of events between the two games. Nova Prospekt was a far smaller part of the gameplay, merely there to provide access to a train, and also included Gunship hangers. Gordon was meant to spend an early part of the game on a vessel called the Borealis, then later travel on a submarine to an air processing facility (which was replacing the atmosphere) to destroy it, that action being the one that began the revolution, then take a plane back to City 17 that would crash into a building.
