Warehouse firefight mod for Half-Life

You are a Gordan Freeman type dood who was left for dead with Barney in a locked room of a warehouse. The warehouse is really just a cover for a Top-Secret splinter government research facility in London that is working on experimental weapons. They tried to kill you because you stumbled onto their secret plans at making a weapon 10,000 times more powerful than a nuclear warhead. You must fight your way through the warehouse complex into the underground Secret Labs to get evidence so you can tell the world about this weapon and head off another arms race. Once you get to the labs you find out that one of their experiments has gone haywire and has opened a rift into our dimension from an alien world. Aliens are pooring into the underground facility and are getting ready to begin an all out invasion of earth. You must fight your way through the aliens and make your way to the few remaining scientists and get them to help you set off one of the smaller doomsday weapons. The explosion in the...