The memorable monster at the center of Stranger Things’ first season was the Silent Hill-inspired Demogorgon, a lanky humanoid figure with flower-like open mandibles in place of a face. Sometimes the monster was a CGI splice-in, but other times it was really there, in the form of a man in a suit wearing an animatronic head. If the Duffers were to nail the 80’s feel, they couldn’t rely on much CG.