DrakeFox: System shock 2 being so ambient you needed to link the same video twice?
Oops! Got carried away. Fixed...
DrakeFox: But is it ambient sounds? The soundtrack works well, yes. And you can hear enemies creeping around as well which will make you sneak down corridors hoping nothing is about to jump out at you until you find a health item, or ammo.
For me I always equated "Ambient" sounds with small sound cues, not music or actual "actor" sounds, but more just background flavour, dripping of water, wind, rattling of chains and such. Maybe I'm way off here.
No, no, I think you're right. Of course, SS2 has that background flavor you are referring to along with other ambient soundtrack happening in the background besides the enemies sounds, voice logs and music. But I don't like to be very strict with forms. To me "Ambient" feels like environmental sounds, like OP says
"the sound of leaves rustling in the wind, winds howling across frozen plains, a creaking wooden structure, machinery/engines in a spaceship etc", mixed with ambient music like Mark Morgans' work on Fallout and Fallout 2.