jefequeso: Let's take this to PM, then?
Actually, I've been enjoying reading this back-and-forth, so please, don't stop on our account.
If you're interested in environmental storytelling, I wonder if you've played ICO? It's one of the best examples I can think of; you can fly through the game and think that it barely has a plot at all ("rescue the girl from the monsters"), but if you pay attention to the environment and start asking questions ("Why did someone build THIS particular castle in THIS particular way? And how did it get like this?"), you can start to piece together an incredibly rich backstory. Which, when understood, actually turns one of the game's most triumphant moments into something deeply horrific.
Riven, the second Myst game, is another great example. One of my favourite bits is the toy you find in the pre-school that teaches you how to count in the native language. And then you start thinking about what it means that they would choose
that particular toy to teach children about counting....
I think the writing term for this sort of thing is "iceberging" - writing a huge amount of backstory, but leaving most of it hidden beneath the surface, with only a few of its implications poking up into view.