First go at this
Managed to construct a list of only films I haven’t seen

6 countries
8 decades
2 insect centered films
1 horror film set in space or the future (relative to when it was released)
2 animated films
1 bloodthirsty old person/people film
2 1970s regional US films (Thanks Sean Young)
The worst horror sequel from the 1990s that you haven't seen and can access. (I realize that this will take a little work)
1 German Silent
5 Films from David Cronenberg, Ti West, Bill Rebane, Charles B. Pierce, William Grefe and/or Joy N. Houck Jr.
2 Christopher Lee films
1 film with a musician or band in it (A real life musician or band)
1 Stephen King adaptation that is not the first go around.
1 Lon Chaney film. (NOT JR)