Shortly after the citadel exploded, Gordon's train was teleported to a beach in which was farther away from white forest than he anticipated. He makes his way through the coastline, caves, and outlands to destroy a combine weapon capable of destroying the rocket in white forest.
The newest storyline of this mod starts at the end of episode 1. The train is teleported to a different location than set in episode 2. And in turn Gordon has to make his way to the white forest complex without alyx.