The horror & experimental variant of the existing KF formula.
Sound familiar?
No idea what the story is, some mercenary guy returns to his hometown to find it gone, with the inverted shadow tower underground.
Decides that he misses some old lady's home cooking so wanders in with just a dinky shortsword.
After finishing it I didn't know why any of this had happened. I think the final boss was the king? Again I don't know.
Visuals are a bit more interesting than the parent series, at least there are now different textures for floors, ceilings, and some furniture/ STUFF that isn't multitudes of gravestones.
No music, but the atmosphere is foreboding as fuck, especially as you could easily be one shot by the next enemy.
Ambient noise, and the enemies' idling sounds add to this too.
Enemy design adds to the dread: some baddies are garden variety spooky, some are grotesque, hints of Eldritch..
Combat is King's Field style again, character has a fast walk speed but no run ability. You can easily run rings around nearly every enemy, again.
The difficulty comes from environmental hazards, or groups of enemies with strong projectiles! Like multi-hitting lasers in rooms with nowhere to hide, that can insta-kill you especially in the early game.
They also go through walls..

Oh and not to mention, one part had me walk through a door and loading screen, which chucked me immediately into some ice-turrets line of fire, which wiped out 70% of my health and killed me very, very quickly.

Possibly the worst thing is how some enemies can respawn right next to you and come out swinging. I took some absolute BS damage because of that.
The game's weapon durability mechanic is the most punishing I've ever seen.
Early on you can easily have nothing but a selection of broken weapons.
After the first 3-4 'worlds' the game gets into its stride: merchants that sap your HP to fix weapons are the safe checkpoints of the game really - while there are more numerous savepoints scattered around, the merchants are your HQ.
I spent a lot of time faffing around using all my life to fix my best gear, before chugging a full heal to fix more.
It's annoying to manage but i think overall it works; doesn't ruin the experience.
Although as if the durability wasn't hard enough to manage: the "Water" world just means pools and pools of corrosive acid that break your armour. It did feel like the game was taking the piss at this point.
The boss fights were kinda decent actually, more so than KF1-3.
There was something unique to several of them at least.
The fact that I can't remember the final boss probably tells you all you need to know.
There's decent item descriptions and lore for every enemy in the game - something usually seen as a hallmark of Souls so it's interesting to see it appear so far into From's past.
Overall I'd say King's Field games are better than Shadow Tower 1.
Real masochistic dungeon crawlers may enjoy this one more, however.
KF gave me more reasons to care and was generally more enjoyable.