Screenshot from Half-LifeYou are Gordon Freeman, a new employee for The Black Mesa Research Facility, Black Mesa, New Mexico. You don't know much about what happens in the Facility, except what happens around your job.

As a scientist, everyday you board The Black Mesa Transit System which takes you to Sector C. There, you put on your Hazard Suit and walk down to "The Test Chamber" and test some sort of unknown substance. Except today is not like any other day, you have to test a very important material, you don't know what, but your fellow scientists have told "the administrator" that "nothing will go wrong".

Except something does go wrong, aliens start to appear around the facility, destroying everything in their path, what do you do? Where do you go? That's for you to find out!