For those scoring sci-fi films or dark ambient tracks, specialized "texture" VSTs are the go-to choice. These often feature massive libraries of recorded "found sounds" that have been processed through high-end outboard gear to sound like ancient, hum-filled technology.
Plugins like Quanta 2 or Portal by Output allow for deep manipulation of "micro-sound," making them perfect for creating the sound of shifting tectonic plates or alien transmissions. Physical Modeling: The Sound of Non-Existent Materials
These plugins excel at "environmental" sound design—the hum of a spaceship engine or the eerie silence of a moon base.
Heavyocity’s Gravity or Slate + Ash’s Cycles are industry favorites for these thick, layered, and hauntingly beautiful tones.