Surviving the house
The rules, not the story.
Moving and acting
WASD to walk, Shift to go faster, the mouse to look around. E acts on what you aim at, F examines, L or right click turns the flashlight on and off, Esc opens the pause notebook. Every key can be remapped in the settings, and controllers are supported.
The reticle changes shape with what you aim at: a hand to take, a magnifying glass to read, a padlock for a puzzle. The object's name and the action are written just below it.
Light
Your flashlight drains while it is on. The battery at the bottom left of the screen shows what is left. Batteries lie around the house: they glow faintly green in the dark. A battery gives back half a charge.
The house has a fuse board, and too few fuses to light everything. Each room has its own circuit: powering one means leaving another without. Light bulbs can be unscrewed and screwed in elsewhere.
A candle you set down lights one spot and stays there, as long as the wax lasts. You need a match to light it.
Fear
In the dark, your fear rises: the edges of the screen darken, you can hear your heart. Light brings it back down. If it overflows, your legs give way, your flashlight too, and you come back to the entrance of the area. You lose nothing you have found.
In the dark you can't make anything out beyond three steps: you have to get close to act. Some things, though, can ONLY be read in the dark.
Reading, and remembering
Every document you read stays in the notebook (pause menu): you can reread all of it. You need light to read.
The pause notebook also reminds you of the current chapter's goal, handwritten, and of what you have already found.
Saving
The game saves by itself at every important step. You can also save from the pause notebook. "Continue", on the title screen, picks up where you were and tells you which chapter.
Comfort
In the settings: brightness, mouse sensitivity, volume, subtitle size and background, language, key remapping. The game's own messages stay on screen even if you turn dialogue subtitles off.