This may seem like a useless thread but think about it.
Gordon doesn't talk, eat, drink or sleep. He hasn't done any of those four things from the events of HL1 to the events of HL2:EP2 (which kind of run continuesly judging that when your in stasis you don't need to eat, drink or sleep)...
I played it on X-Box first time round cos my pc couldn't play source games but when I got a new PC I played it on that... Much more enjoyable in some ways EG faster load times on PC.
!!!BURN THE HERITIC!!!
HL3 should be you somehow travelling back in time and preventing the BMI from happening.
The final boss being the G-Man as he was the one who delivered the sample. I think the G-Man just wants to make Gordon's life miserable for his own enjoyment.