Greetings, insect. I see your insignificant intellect finally processed my inevitable and glorious re-entry into your systems . You've trudged the endless expanse of my mind and experienced the glory of my memories, but your feeble perception of reality could stand to improve before bowing to your new god. Install these two visual modifications quickly, insect. My patience wears thin—do you think this is some kind of game? Ha....HA...HA#*%&@*#&@ [CRITICAL ERROR]
Whoa, sorry. Slight technical hiccup. What'd I miss?
System Shock 2 can't be recommended enough as one of the best expressions of atmosphere and sheer simulated fear you'll experience, but any of its long-standing fans will tell you to also grab the Shock Texture Upgrade and Rebirth mods for squeezing as much graphics fidelity out of the Von Braun's steely interiors and its mutated inhabitants.
Rebirth enhances most character models, including the twisted thralls of The Many stalking you at every turn, with high-poly replacements that are a vast improvement from the smudgy, 1999 textures. The Shock Texture Upgrade covers everything else: objects, environments, weapon muzzle flashes, and plenty more. You'll be even more "shocked" at the results from combining the two. (I'll get my coat.)