Monster closets didn't scare me at all, not even the first time. They just shit me to tears in short order.
For me, graphics are a big part of any FPS game. Apart from storyline deviations, every damn FPS game is pretty much the same thing over and over. For innovation, I think Nolf had HL2 and D3 beat hands down.... and it didn't have a gravity gun;P Don't think it has physics of any description, either..... but you can still speargun people to walls.
As for the nipple monster.... I've worked him out. It's Raven's subconscious way of letting us know Quake 4 has titillating gameplay.