Alright, so this has been bugging me for a while, so if anyone here could help that'd be stellar. Here's what I posted over on /r/tipofmyjoystick:
Platform(s): I played this on the Playstation 2
Genre: War, Third/First Person Shooter (can't remember)
Estimated year of release: 2000's, possibly and most likely post-2005
Graphics/art style: Realistic
Notable gameplay mechanics: The ability to switch between characters within a single mission. From what I can vaguely remember, you could see a character in the distance, say on a watchtower, and a prompt would appear. Upon pressing X or whatever the prompt was, you'd then play the game from that soldier's perspective. You could switch between soldiers on the map at will.
Other details: The levels I remember playing were set exclusively in the snow. I remember some sort of abandoned factory, also a bridge and preventing a helicopter from doing....something.