More details from the dark source, here.

There must be 31 horror films, and I'll track 'em as I go. What follows is a work in progress (started early because I was excited and impatient).

31/31 horror films
14/6 countries (other than Italy or US): Spain, Canada, Korea, Mexico. Cameroon, Japan, Hong Kong (as BDTC), France, Lithuania, Ukraine, Estonia, Latvia, Russia, UK
10/9 decades: 1930s, 1940s, 1950s, 1960s, 1970s, 1980s, 1990s, 2000s, 2010s, 2020s

6/5 zombie Films (Tombs of the Blind Dead): Night of the Seagulls; Train to Busan; Night of the Comet; Shock Waves; Zombie (Flesh Eaters); Swamp of the Ravens
3/3 cult or conspiracy horror films: Night of the Seagulls; The Sect; Shock Waves
2/1 film from a Black director with a Black lead: The Blackening; Les Saignantes
1.5/1 film from a Mexican or Central American director: Rapiña, Perdita Durango (US-Mexico co-production)
1/1 Canadian film: The Incubus
4/1 former Soviet state film: Rūpintojėlis (Lithuania), Cycle (Ukraine), Kratt (Estonia), Upurga (Latvia), Sorceress (Russia)
1/1 most popular film from the 1940s that you haven't seen and can access: The Spiral Staircase
2/2 post apocalyptic horror films: 28 Days Later; Night of the Comet
3/1 film with dreams or a dream as part of the plot: The Incubus; Beyond Dream's Door; Slumber Party Massacre 2
1/1 the animals are pissed at us film: Ben
1/1 silent film: L'Ange
4/4 based on novels (Wizard of Oz): The Spiral Staircase, Perdita Durango, The Incubus, The Most Dangerous Game (based on a story, I know, so I may replace it)
6/1 film from THIS list that you haven't seen: I Drink Your Blood; Night of the Comet; The Blackening; A Chinese Ghost Story; Zombie; The Burning
1/1 Ernesto Gastaldi written film: Libido
1/1 film from 1932: The Most Dangerous Game
& WIZARD of OZ ('39)

Extra credit:
1/1 Trick or Treat

And 1/1 Tobe Hooper film (There must ALWAYS be a Hooper film): Spontaneous Combustion

***FOR THOSE THAT LIKE TO DO EXTRA WORK: WATCH Burn Witch Burn, German Chainsaw Massacre & Trick or Treat (1986).