I guess I'm writing some sort of book, about Half-Life 1, for Brendan Keogh / Dan Golding's new recently sort-of launched book publishing project. So what's there to say about Half-Life?
I know I definitely don't want to focus on Half-Life's authored narrative (dialogue, scripted sequences) or "environmental storytelling" -- I think that approach is played-out, and the promise of that approach has proven to be a failure -- it's convinced so many game developers that a ragdolled corpse with some blood and bullet decals is supposedly a "good story" instead of a weak, generic vignette that's not really about anything. Two ragdolled corpses next to each other isn't a good story. A chair with a shotgun next to it isn't a good story. There are very real limits to this methodology if that's the most "subtle" we've been.
Instead, I want to recast what Half-Life's legacy is: it is the game that popularized realism in level design, use of squad enemies who hate other squad enemies, and those "turn the valve before you die" progress gates, among many other design patterns. What is Half-Life's larger contribution to craft, tuning, pacing, and design?
Almost a decade ago, I worked on a large high-profile Half-Life 1 mod -- many of its members are now mid-level or senior staff at Valve, Respawn, Bungie, Gearbox,
... and we all cut our teeth on Half-Life 1: its design sensibilities, its physics, and its approach toward player experience. Even today, my folder structures and game infrastructure often resemble Half-Life's way of doing things -- so when I'm trying to tune movement physics in other games, am I just trying to replicate the feel of Half-Life because that's what feels "right" to me? (Unreal Engine games almost all universally feel "chunky" to me, in comparison. I'm sure people who grow up using Unreal would disagree with me, and argue that Half-Life or Quake-lineage games are too loose.)