Most of the things they do I would consider gimmicky until I played; you walk really slow unless you're sprinting (not good for combat), your flashlight runs on a battery you have to charge with a little dynamo, and in some places you have to wear a gasmask, which can be broken in combat.

Again, gimmicky, except I really tended to enjoy all of those additions; the gas mask segments are pretty unnerving, especially if you don't see a spare nearby or if they're all somewhat cracked. Its adapted from a novel, and it shows: there are plenty of cutscenes, but they too seem to fit snugly in without any complaint; there's also little excerpts (or abridged stuff) read aloud during level loads. Fun game. Impossibly hard. Play it.