Very in-depth topic... I like "Stephen King" works so I'm glad that Steam founders took inspiration of one of them.
HL uses this train ride to show you the research facility daily routines, thus establishing the world and giving you time to enter the mindset of an everyday scientist working on secret government projects.
Very ambitious of a game at that time... I started to think the Half-Life I played was the first game after reading this... most of the things that Game did are normal/old by today's standard though.
It was very interesting read!! good to know about the expansions it had... didn't read the last parts of the post as I don't have much time right now so sorry... But I might do that later.
Half-Life was revolutionary. Alot of the things it introduced into the mainstream then, are still commonplace now, though more polished.
Pretty much all Valve games are good at least in one aspect. But it is surprising they had this much of an impact straight out of the gate.