Disclosing up front that I was a playtester on this, but also it's some of the most fun I've had with a dark fantasy ttrpg full stop.
Hollow Halls is a Fear & Hunger / Darkest Dungeon inspired grimy crawler, where combat is lethal and exploration is dreary and ominous.
Fear & Hunger *is* the primary part of the formula, and a lot of its more immsim elements are preserved. You have the Resident Evil 4 suitcase inventory, and it's also the targeting grid for your character, so attacks can damage your weapons, or items, or empty squares. Even breaking or removing them.
Targeting is done by rolling randomly and then spending points to adjust. Foes can spend these points too, so part of combat involves running enemies out of resources so that you can hit them cleanly. It's surprisingly fluid for how complex it is, and every hit ends up feeling weighty and meaningful.
Setting-wise, Hollow Halls leans on atmosphere and implication, showing more than it tells. That said, it's easy to create characters for. There's enough of a primer to know where to situate people in the setting, and each class comes with a strong sense of identity.
As far as its horror elements go, Hollow Halls is primarily gothic and violent in tone. It doesn't carry over any of the erotiphobic horror from F&H, and it doesn't rely on coinflips and instadeath to sell its lethality.
Ultimately, if you like grim and precise rpgs with hit location charts, this should be at the top of your read list. It kinda casually revolutionizes the genre.