Ph'nglui mglw'nafh Cthulhu T'leth wgah'nagl fhtagn.
- Terror From the Deep didn't get its name for nothing. Essentially, it's UFO Defense mixed with H.P. Lovecraft. The aliens you fight are the stuff of nightmares, especially the Tentaculats and Lobstermen. To clarify on the latter, the Lobstermen are giant crustaceans that can shrug off any attack that isn't a melee weapon, while tearing your own troops to pieces if you are not prepared.
- The Tentaculats. For one, you only encounter them at Alien Colonies, Artefact Sites and large Submarines. There's a good chance you'll be fighting them in the dark, which adds to the creepy atmosphere all to well. Second, they look like giant tentacled brains with huge octopus-like beaks. They do the same thing as Chryssalids, except they can float.
- Many of the aliens in this game indulge in Body Horror. The Deep Ones are humans that were grafted with Aquatoid DNA in the most gruesome way. Bio-Drones are piloted by brains that were butchered into submission, and use a sonic beam based on their original vocal cords to scream their enemies to death. Blessedly, the UFOpedia notes that most of the brains that power them are alien in origin, "but nothing can compare to the horror of finding a human based unit."
- The Chamber of the Ultimate Alien is surprisingly creepy. The Alien itself resembles a huge aquatoid with a Cthulhu-like tentacled face and is in a coffin shaped "bath". However, the creepiest part is that its reanimation process is powered by 8 alien fetuses/babies in glass jars. Which then writhe in pain while getting electrified after you shoot the glass, which you need to do to kill the Alien.
