It happened several years ago, I was playing late at night, with headphones on and all, and I walked into a dimly lit corridor, and I saw a figure of something. In my tiredness, I wondered; "Is that a cactus?" I walked over to it and studied it for maybe a full second, and I pretty much jumped in the chair when it punched me in the face. It was one of these
But honestly though, I can't remember it being a very dark game. I don't think it is meant to be played as a dark horror game with low brightness, but more as a fast action-game with awesome weapons and a metal-soundtrack. It might enhance the visuals to play at low brightness though, as bullets and rockets will emit light, and thus look nice in the gloom. I don't know if there is a definitive setting to play the game at, but just find the setting that suits you :)
Thanks, I'll do that.
I just didn't want it to be like Thief where you can up the brightness but then you can see stuff you aren't supposed to be able to see which is pretty much cheating. :P