The sequel Robert Bloch wrote was a critique of splatter movies Hollywood like the book so it commissioned whole new script for movie What it?

The sequel to Psycho written by Robert Bloch was titled "Psycho II" and was published in 1982. While the novel did feature some criticism of splatter movies, it was not the primary focus of the story.

The movie adaptation of "Psycho II" was actually based on a completely new script written by Tom Holland, rather than an adaptation of Bloch's novel. While the film does contain some elements from the novel, the plot and characters are quite different.