When you hear the phrase “gateway horror,” what comes to mind? The phrase is frequently thrown around when discussing modern cinema, serving as a perhaps gentle way of saying something doesn’t cut all that deep but could lead to discovering other better genre films that do. Typically used to describe the audience’s journey, it ought to also be used to discuss filmmakers who are figuring out their own path into a genre.

In “Hell of a Summer,” the lightly humorous yet oddly undercooked feature debut of co-writers, -directors and -stars Finn Wolfhard (“Stranger Things”) and Billy Bryk, every element feels like it’s a gateway to what could be a solid enough film. Alas, despite it trying to take parts of better horror films (including its John Carpenter-esque score), it never arrives there in one piece. The familiar premise, which involves a group of young counselors being...