All 16 words, sorted alphabetically. Group them into four categories of four.
The four category names, easiest to hardest. No words revealed yet.
Theme name plus one word from each category.
COSMETIC, ONE-DIMENSIONAL, SKIN-DEEP, and SUPERFICIAL all mean shallow or lacking depth, describing things that only exist at the surface level
HYPERSPACE, PARALLEL UNIVERSE, TELEPORTATION, and TIME WARP are all classic sci-fi phenomena that involve bending or transcending the normal rules of physics and space-time
THE GREEN MILE, THE LONG WALK, THE RUNNING MAN, and THE SHAWSHANK REDEMPTION are all Stephen King works that were adapted into films
HARLEM SHAKE (shake), INSIDE SCOOP (scoop), LICKETY-SPLIT (split), and TRAFFIC CONE (cone) each end with a word that is a classic ice cream order or vessel