 When Dr. Gordon Freeman, a scientist who is a research associate at the Black Mesa Facility in New Mexico, is assigned the task of helping out the scientists in the Anomalus materials lab with an experiment, things go horribly wrong when the artifact gets jammed into the emitters and opens a portal to Xen, an alien planet where an infestation has begun on the facility. As, Gordon Feeman, you must fight your way to the surface from the laboratory you started in, to the lambda complex on the other end of the facility, to teleport to Xen and stop the infestation of aliens. Along the way you will need to pick up weaponry such as close quarter weapons, pistols, machine guns, shotguns, crossbows, experimental weapons, and explosives. You will encounter many aliens, who bite, shock with electric current, shoot, and even poison you. And if things weren t bad enough, you have the military to try and kill anyone associated with the project and the aliens themselves. You also must seek the help of the scientists and Barney, the Black Mesa security guard who is quite useful in combat. Good Luck!