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.
Stumbling upon this while moving old files onto an external hard-drive, I'm at a loss as to how I acquired this, seeing as how the mod is no longer in development (saves indicate I last played this in april 2012) and after giving it a go again, it was a mixed bag.
Most of the levels are obviously unfinished, buggy and misaligned, with most requiring console commands to run.
What story there is, isn't something to brag about. However, the large number of custom mapping assets, textures and models really show how dedicated the team was trying to assemble a mod, with plenty of new special effects and even some very impressive scripted events and cinematic physics at work!
However, it is incomplete and cobbled together. If you really want to see what could have been an interesting mod, drop me a line, I can see if I can upload the file somewhere :)