Alright, mental failure on my part. It's what I get for staying up all night. He modified the Mark IV, but he didn't do so while Gordon had it... so he salvaged one from Black Mesa and updated it, or... designed a new one from scratch.
The latch on your door clicked?
Did you touch it, or did it do so on its own?
Have you had any feelings of anger, fear, or remorse?
From what I've seen, these shadows are drawn to negative emotions.
Or... are there other electronics in your room besides your computer?
You could be living in...
The fact that you end Half-Life 1 with the Mark IV, and begin Half-Life 2 getting the Mark V, and Kleiner would not have had much of a chance to work on it while escaping black mesa, the original portal storms, or the 7 hour war... so it had to be somewhere between HL1 and 2.
The answer is cake... and we all know the cake is a lie, so that in turn means the table is a lie... and I can further expand it to say your existence is a lie.
Our own shadows... but sometimes they're not our own, and that's the innate fear.
Maybe you feel a collection of shadows as it's the corrupted lives of all who have come into contact with the coin... you weren't the first to get it, and you won't be the last.
The teeth and claws might just...
I wouldn't mind seeing some third-party continuations (or even side-stories like Opposing Force/Blue Shift), have them shift things over to a third party to keep people interested while they're cranking out the next game.
"something" could also be a concept... "something" is too vague, it can be anything... and if something = anything, then who knows where else this could lead to...
Well, just randomly messing around with it...
Whoa, and I just noticed I posted it up 10 minutes after the original post... so someone else had better come up with something good.
Darkside, your story intrigues me. One day I went over to my friend's house and felt a strange feeling of being watched while I was in his upstairs hallway... I thought nothing of it at first, but I asked later about it and he divulged some details that I find strikingly similar to your story...