The Havok engine is being used for real-time physics within most environments. Bumping into chairs, desks, weak floor boards, with produce noises that alert enemies to your presence. We're sure domino effects are likely too: knocking a chair into a table could knock a lamp down and break it (where there is, of course, a hidden key). Much like the film, Silent Hill 5 is going to employ real-time world deterioration. The transition between the normal world and the world of ... well, the messed-up world, will be visible in real-time and you can move the camera to check it out in great detail. That's some exciting stuff.
A final note is on the revival of boss battles. Bosses have been fairly tame in the Silent Hill games outside of the first and third, which featured large, monstrous bosses. The Collective, the game's developers, want to bring epic boss battles back into the game, relating the experiences to Zelda-like encounters. We're interested to see how that works. We'll keep you up to date as more info gets released.