Asklemmy

Half-Life as a live-action film, in continuous first-person.

The game is deliberately cinematic to begin with. You'd cut down a brisk run-through to maybe an hour of set-pieces and combat, then build out the "dialog." In quotations because I would make Gordon canonically mute. It'd become thematic.

Gordon took the hazard course qualifications that secretly exist to staff the extraterrestial excursion team, but they're not quite desperate enough to risk having an astronaut who can't use the radio, so he's stuck on Earth pushing rocks. Without a helmet, because the excursion team keeps losing equipment, what with getting attacked by aliens. The aliens think the guys in orange suits are a distinct subspecies... which keeps kidnapping their kind.

Vortigaunts in particular would be seen maybe trying communicate with scientists in labcoats (a subspecies marked by their ridiculous ties) only to spot Gordon and freak out. They all hate the POV character on-sight. If they're on-camera, they're gonna start waving their hands to cast deadly lightning. They'd even try to communicate with the bug-eyed subspecies in splotchy green outfits, only to get shredded by submachinegun fire. The military wears those dehumanizing masks (and speaks over radio comms you can hear) because all they were told is "secret experiments, actual zombies, existential threat." They saw one distended human with a jaw for his ribcage and the strength to slap a dude in half, and they didn't ask any further questions.

This all comes together in Interloper. Gordon sees the biological factory where these creatures are enslaved to manufacture more of themselves. The ones inside know nothing about Earth. They prance up, curious and burbling incoherently, pawing all over Gordon's bright orange carapace. He sticks a gun in their faces and they consider the object fascinating. But when he puts it away and tries communicating in sign language, they scatter, and a few start waving their hands to zap him. Gordon Freeman was chosen for this event because he is physically incapable of any outcome but one.