I know I've been at this a minute when I can't meet the criteria without including a few films I've already seen. Where possible, I tried to at least go with ones I haven't yet reviewed.

Original list: letterboxd.com/cinemonster/list/hooptober-x-hooptober-hooptober-let-satan/

There must be 31 films

6 countries:
USA (The Amazing Mr. X)
Mexico (The Aztec Mummy)
UK (Blood from the Mummy's Tomb)
UAE (Djinn)
Japan (Gamera vs. Gyaos)
Australia/New Zealand (Next of Kin)
among others

8+ decades
1920s (The Unknown)
1940s (The Amazing Mr. X)
1950s (The Aztec Mummy)
1960s (The Deadly Bees)
1970s (Beyond the Door)
1980s (Angel Heart)
1990s (Alien Resurrection)
2000s (Book of Blood)
2010s (Djinn)
2020s (Shaky Shivers)

2 post apocalyptic or natural disaster related films (Day the World Ended, Vanishing on 7th Street)

1 film with Robert Englund (The Fifth Floor)

1 something is underground ("Underground"?) film (Death Line)

3 Satan/Devil centered films (Angel Heart, Beyond the Door, The Day of the Beast)

1 Amicus film (The Deadly Bees)

The worst Dracula film (by Letterboxd rating) that you haven't seen and can access (Dracula 3D)

1 LGBTQ+ connected film ()

5 Films from De Palma, Wes Craven, Ken Russell, Hitchcock and/or Moorehead & Benson (Cursed, The Fury, Gothic, Swamp Thing, Vampire in Brooklyn)

2 Peter Cushing films (The Flesh and the Fiends, The Hound of the Baskervilles)

1 film based on a work of or invoking the name Bram Stoker (Blood from the Mummy's Tomb)

1 film based on a Clive Barker story (Book of Blood)

1 film that was released the year that you turned 10 (Next of Kin)

1 Mario Bava film (The Whip and the Body)

1 film with an 'x' in the title (The Amazing Mr. X)

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

***FOR THOSE THAT LIKE TO DO EXTRA WORK: WATCH The Zodiac Killer and 10 Rillington Place. Like last year, there is a third film: Shaky Shivers.