Nine hundred years ago somebody built a fortress here and sealed it the day it was finished. Every course of its masonry was laid on that same day, which is not how anybody builds a fortress. Fourteen people opened it. You are not one of them. You came down afterwards, through the same doorframe, long enough after that their lamps have gone out and their handwriting is still on the walls all the way down.

A dungeon that answers

Blackmere's corridors are not laid out. They are answered. The Black Sun the instrument the expedition carried down does not make light. It asks the dark a question, and the dark answers for a few seconds at a time. Ledges, ground and whole routes exist only while something is asking about them. Move while it is talking

Four weapons, and no fifth

The Regent's Cleaver, the Warding Bolt, the Splinter Lance and the Black Sun. Only the sword is yours at the start; the other three are found where the expedition dropped them. Nothing after the fifth chapter hands you a weapon  the back sixteen escalate by what the rooms ask of you instead. Fight with one long enough and it ascends into a stronger form.

Kills bank toward a choice of three rites, and the ones you take are permanent for the run. There are eight, and you will not see all of them in one descent.

A story you have to look for[

Thirty seven notes are scratched into doorframes, stall ends, ration tins and the plate of a dead Bulwark. Every one of them is optional, which is the point. Read them in order and they are one continuous account of what the fortress did to the fourteen, written by people who worked it out too slowly to help themselves

Twenty one chapters and three encounters

Three acts, seven chapters each, and something waiting at the end of every one. A flooded archive, a sluice, a kiln, a ropewalk, a bellows nobody has fed in years, a choir singing under the water in four parts. Then the gate, and everything under it. No map, no waypoints, and the exit is not where you would like it to be

Movement with weight

Tuned around one idea: somebody carrying a lamp down a hole. High acceleration and a modest top speed, a turn-around that pivots instead of skidding, a float near the apex of the jump that has to be asked for, and a weak second jump that is a recovery kick rather than a free storey. The dash attack is a flat lunge that cuts everything it passes through and shortens its own recovery for every target it hits  it is a movement tool and an attack at the same time, and the correct use is to go through something rather than away from it

What you will be fighting?

• Eight kinds of thing, and none of them is a reskin: a shuffling Hollow, an armoured Bulwark that has to be baited into a wall, a Lurker disguised as rubble, a Quarreller that refuses to be stood next to, a Scuttler that walks on ceilings, a bolted-down Sentinel, a diving Wisp, and a Chorister whose only counter is forward.

• Three bosses, none of which shares an attack with another.

• Full keyboard and-mouse or gamepad support, with a waystone checkpoint system