Whats the best system for horror dungeon crawling with a dark and claustrophobic amosphere ala the first Diablo?

Whats the best system for horror dungeon crawling with a dark and claustrophobic amosphere ala the first Diablo?

Ok hate to be the first poster and posting this but G.U.R.P.S.

Possibly some OSR. I quite liked The Black Hack when I read it, though never played it. Lamentations of the Flame Princess seems popular as well.

Oh, I forgot DCC (Dungeon Crawl Classics). That one's pretty cool too.

WFRP comes to mind as having explicit mechanics for insanity/corruption, but honestly when trying to emulate mood/tone the actual way your run your campaign and what you put in it matters equally as much. If you want a dark and claustrophobic atmosphere use dark and claustrophobic dungeons.

Enforce lighting, reveal bits of the dungeon in the dark. Have enemies move around in the darkness at the edge of the lantern light and describe the sounds of them shifting. Cover all the revealed map up if the party loses the light, or the like.

Solid game procedure and enforcement of resources like lighting does a lot, assuming you're using a system with appropriately powerful PCs (i.e. don't pick something where everybody gets darkvision)

Torchbearer is LITERALLY built for this. Resource management (your light source itself being a primary resource), horror, despair and a dystopic, decaying world whose best option is to raid cursed, haunted or simply dangerous ruins. Bonus points for classic fantasy roles.

I've heard good things about Shadow of the Demon Lord

Steal mechanics from Darkest Dungeons.
Set up a way to measure stress and make it have an impact on rolls. Some abilities used by PCs causes stress to go up, as well as abilities used by enemies and effects linked to the environment.
Make rules for light. The darker the room, the tougher the monsters.

And put the Tristram soundtrack on repeat.

Djling-djling-djling. Djling-djling-djling.

Torchbearer has all of these built in.