Half-Life 1 and 2 rank among my all-time favorite video games. HL1, especially, has a great story, which is hard to pull off in a first-person shooter. Being a science fictional setting, there's a lot of fantastic stuff that requires suspension-of-belief: murderous monsters, teleportation portals, alien worlds, futuristic technology, and the fact that all the scientists at Black Mesa have the same face and voice. Given all that, there was one that actually bugged me: the fact Gordon Freeman, the protagonist, could carry several hundred pounds of weapons and ammo and run sprints without breaking a sweat. To recap, by the end of HL1, Gordon is carrying:
Not content with "it's just a game, stupid" my brain has rationalized how one Navy-Seal-turned-high-energy-physicist could carry all this, and what's more, it's actually a major plot point.
The key is the HEV Suit. If Gordon Freeman is the archetypal hero of myth, the HEV Suit is his magic armor. It protects him from injury, aids healing, allows him to run faster, keeps track of vitals and ammo, talks to him in a friendly robo-feminine voice, and even has a handy flashlight. It is what sets Gordon apart from other actors in the game, what gives him power beyond mere mortals.
And it's why the military is after him.
We are told in the beginning that the HEV suit is merely work clothes, something a third-tier physicist wears while doing the grunt work for the Big Name scientists at Black Mesa, all the while hoping he'll be listed as fifth contributor on a journal paper or three. That just what we're told. In reality, it's a prototype military exo-suit, outfitted with advanced technology gleaned from Black Mesa's dalliance with portals. Specifically, it uses portal-based technology to create extra-dimensional "pants pockets" where Gordon can stash his arsenal without being encumbered. Doctor Who would be proud, possibly even jealous.
It's pretty clear the suits are rare:
Given how powerful the suits are, it's no wonder the military wants them. And it's quite possible Gordon has the only one left on Earth. So when the soldier come in and start murdering scientists left and right, they aren't just securing the facility and erasing every trace of Black Mesa's existence. They're also after control of all the cool weaponized tech -- including Gordon's HEV suit. I mean, they wouldn't want him getting away and selling it to Aperture Science, now would they? And in the end, they get it, or at least, the G-Man gets it when Gordon agrees to be his flunkie and go into suspended animation for 20 years while the Combine invade and enslave us all.
Fortunately the other Black Mesa survivors (likely Dr. Kleiner or Dr. Vance) were (conveniently) able to re-build a new HEV prototype just in time for Gordon to re-awaken in HL2. At that point the world is already conquered by forces with much cooler toys, so Gordon is pursued less because he's wearing a mechanical orange jumpsuit and more because he's a frickin' Buck Rogers, a legendary hero come back from the dead to lead us out of slavery. If he doesn't hog all the medkits, that is.