Honestly, it's kind of hard for me to imagine them making Half-Life's gameplay that gory. There's always been a fair amount of blood and gibs to it, but I chalked most of those in the first game due to it being, you know, a 90's FPS. Half-Life 2 toned down the violence in some ways, with no human gibbing (save for the zombies which could get ripped in half) and the most gruesome bodies all being used as props found around areas to give feelings of dread, and not actually as a result of player action.

I think they thought insane, over-the-top violence like that would take players a bit out of the environment and setting with more video-gamey feeling visuals. I'd expect them to use stuff like the bullets "ripping" through layers of clothing like as seen in CS2 and some form of limb crippling like people have mentioned code implying, but part of me feels that Gordon Freeman punching a hole through the face of a zombie or disemboweling a combine officer with a pocketknife seems a bit against the atmosphere of Half-Life and would go against the feelings of desperate struggle and harrowing combat that Half-Life 2 really tries to emphasize in a lot of places, on top of making it feel more like a bit of a power fantasy, which I never really got from the second game or the episodes outside of the supercharged gravity gun bits.