So I've been replaying HL2 plus episodes recently, and a kinda theory about the plot/lore came to me. Through all of HL2 the environments represent urban decline, abandoned buildings, industry and factories are everywhere. It seems like NOTHING works in City 17 except the Combine technology. So perhaps the reason is because the Combine technology has made the "old" human technology and industry completely redundant. When you're inside the Citadel you see the Combine churning out Dropships, Gunships, Striders etc at a ridiculous pace, so it makes sense that in the face of this superior tech that the government has abandoned the old economy.

Thoughts?

G-man was Gordon Freeman the whole time.

Now that's a theory one can sink one's teeth into! Half-Life 3 will feature an aging, clean shaven, suit wearing Gordon Freeman who's had eye surgery so he doesn't need glasses, and will consist of lots of time travel puzzles, making sure that his younger self does all the things he did in the first two (four if you count the episodes as such) games.

I always thought he was The Cigarette Smoking Man with a rather strange speech impediment. So if we're going with that metaphor he's actually Gordon's father.