QUICK EASY RULES:
There must be 31 films

6 countries
Possession (Germany/France), Cure (Japan), [REC] (Spain), Suspiria (Italy), A Tale of Two Sisters (South Korea), Goodnight Mommy (Austria)

8 decades
Possessor (2020), Us (2019), Saw (2004), Ringu (1998), Halloween 3: Season of the Witch (1982), House (1977), Black Sunday (1960), Diabolique (1955)

2 insect centered films
Mimic and Them!

1 horror film set in space or the future (relative to when it was released)
Event Horizon

2 animated films
Mad God and Paprika

1 bloodthirsty old person/people film
Relic

2 1970s regional US films (Thanks Sean Young)
The Last House on the Left and The Driller Killer

The worst horror sequel from the 1990s that you haven't seen and can access. (I realise that this will take a little work)
Candyman 3: Day of the Dead

1 German Silent
Nosferatu

5 Films from David Cronenberg, Ti West, Bill Rebane, Charles B. Pierce, William Grefe and/or Joy N. Houck Jr.
Rabid (Cronenberg), The House of the Devil (West), The Town That Dreaded Sundown (Pierce), Sting of Death (Grefe), The Sacrament (West)
***EDIT: Literally cannot find a copy of Sting of Death anywhere, so unfortunately having to skip that one***

2 Christopher Lee films
The Wicker Man and Dracula (1958)

1 film with a musician or band in it (A real life musician or band)
The Hunger (David Bowie)

1 Stephen King adaptation that is not the first go around.
Carrie (2013)

1 Lon Chaney film. (NOT JR)
The Phantom of the Opera

And 1 Tobe Hooper Film (There must ALWAYS be a Hooper film)
Poltergeist

***FOR THOSE THAT LIKE TO DO EXTRA WORK: WATCH The Last Circus and Silent Madness. Like last year, there is a third film: Pennywise: The Story of It.