Bridge Horror House: three keys, a torch and batteries as currency
First-person horror usually opens with a single promise: you are locked in, you need to get out. Here exactly one detail was added to that promise, and it rewrites the whole game. The detail is the torch. It is the only weapon against whatever walks the house, and at the same time it drains batteries five times faster than a torch that is merely on. That one number turns "get through the level" into resource management: hoard the beam and walk half blind, or burn the thing following you and end up in a dark house with a dead cell.

Three keys, and no map
One key hides in the kitchen, one in the study and one in the bedroom, and every run picks a new spot out of three candidates per room. What follows from that is a design decision that is rarely made: the player needs no arrow of the kind. What the player needs is the sound of footsteps in the next room and a guess that the far corner has not been checked yet. The randomness here is not decor shuffling — it changes the route every time, and the route is the actual content of an escape.
He does not come straight away
While one key is found, the house offers nothing but a creaking door and footsteps. From the second key a breathing layer appears and the vignette starts to pulse — the stalker is already close, but still unseen. The last key wakes him fully: the lights die and all that is left is running for the door by ear. That three-step ladder works because the player gets used to the silence first, and then the silence is cut — the cheapest and most reliable trick in horror, because it trades on anticipation rather than on jump scares.
Not a single image in the project
All of the graphics is code: wallpaper, floorboards, damp stains and the ghost's face are drawn on a canvas and applied as textures. The audio is synthesised in the browser as well — creaks, footsteps, breathing, heartbeat, with the pulse rate climbing as the thing closes in. For a browser game that is convenient for two reasons: the frame never depends on image sizes, and the page weighs less than a megabyte, horror included. The second point shows up clearly here, since the whole engine is about a megabyte and most of it is three.js itself.
Light you have to save
Battery packs are scattered around the house, each one adding 45 percent. So the question "is it worth burning the beam right now" is answered literally on every step: if the thing is far and unseen you can afford to keep the light off; if it is close, banishing it drains five times faster and the reserve stops being an abstraction. Alongside them are two notes that explain the rules in story language: "Night 41. He cannot stand the light." The game teaches its own loop through two sheets of paper, and that works better than a tooltip ever does.