If you loved The Fly, try Shivers
A bridge between a film you've already seen and one most people haven't. Shivers has roughly 7.0× fewer votes than The Fly — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by David Cronenberg, and they both carry the body horror mood tag, and they sit in Horror / Science Fiction territory. If that's the register that drew you to The Fly, the second film will land in a comparable space — through a different lens.
What Shivers is
Île des morts. Mid-winter. A single maggot. Luxury condos become a hotbed of perverse contagion after a mad scientist’s aphrodisiacal parasite gets loose. The sleek building turns into a breeding ground. Cronenberg's early body horror is less gross than you remember.

