I'll state an old classic that is seen as a genre defining game because it is: Myst. Yes, it redefined the genre... in ways I fucking hated and that the adventure game genre took decades to fully recover from. It was a pompous mess in its presentation and was the worst kind of "doing action does vague thing or nothing at all, where is your hint book" puzzle gameplay wrapped in graphical hype which ages pretty poorly as far as appeal qualities go.
So many adventure games tried to be Myst afterward that the sheer budgetary costs and redundancy of the also-rans crashed the adventure game genre for years.
I've been playing Environmental Station Alpha in my desperate search for literally any modern Metroidvainia (I'd give it like a 3-4/10 in terms of having a Metroidvainia structure). Holy shit Overgrowth is the most annoying boss I've have seen in a long time and the game in general is just tedious as shit and full of hitting your head against different walls both figuratively and literally.
I am begging whoever might have this information about where a good Metroidvania other than Hollow Knight is.
It starts linear but widens out quite early on, (it's been a while since I've played it but I kinda recall it opening up after the first non-tutorial boss).