This is Chapter 4 of the Black Mesa Incident...
System: reboot completed.
Okay... Another great day... But not so great. I was now on another place. There was a scientist over there yelling at a guard and he was like a insane psycho banging a window.
"OH MY GOD! OPEN THE SILO DOOR!"
The guard got caught by a zombie, got dragged into the vents, and then got killed. The scientist was getting so insane and he was out of his mind. He ran towards a laser-camera but as he pass through it, the scientist died because the camera exploded. And I was like, "Oh god! I got to get one of those things so I could trick someone."
There was more ammo and I saw a scientist running to a Marine. I thought I was now safe. What a fool again! That Marine killed him and so he shot me. I thought he was out of his mind and when I killed him, I grabbed his M4A1 and still got 3 more rounds. There was a lift next to the dead scientist which I used and it led to the surface.
As soon as I got out from the big hangar, the surface is there, the bright sunlight. And the asphalt road. Little I know, the other Marines kept shooting me and I was still trying to think that they were all crazy but I knew the reason they wanted to kill me. Because I was the primary target.
A few minutes outside. I was forced to crawl into a hole leading underground and I was no hope for escape when they are bombing and sending more troops. I got further down to Black Mesa and grab a few ammos and then there was this thing called Barnacle that caught someone or something that touched its tongue. More Soldiers came and their patches says: HECU Marines.
They had come to kill me and after a few mazes, I managed to crawl to a vent that led to the Silo Door control room where the guard was killed. Another scientist was over there that came before me. He said:
"Gordon, I am hiding here and watch out for those Soldiers! They are sent to silenced the remaining personnel alive including those who are part of the experiment. Specially you. But be careful Freeman! Don't get killed."
I click the button that opens the Silo Door. And now, I'm gonna face a big yet dangerous thing that is very aggressive and sensitive.
Credited to VALVe for using their storyline.