Started something. Not really sure about exact mechanics but have a couple of ideas. May be about shutting doors and windows. Here's what is known:

• happens inside a house
• first person perspective
• minimalist 3D graphics
• somewhat dark
• generated/randomized room layout

I'm starting with technicalities rather than vibe. Set up a house generator that spits out house layouts by recursively subdividing a rectangle. Geometry is generated using Godot's convenient CSG primitives. Hope those perform well.

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The generator now places doorways between adjacent rooms. It also figures out which rooms don't have outside walls (marked in red). Those rooms cannot get wall windows. Could be useful later on.

Implemented a simple player/camera controller, featuring standard wasd movement and mouselook.
Also added a reticle.

loving your development so far! I’ll have to post mine soon as well to get the ball rolling

Implemented the ceiling and the holes. The ambience is getting somewhat closer to what was intended. The generator is now able to figure out the outer walls and put window holes into them. Ditto for ceilings. The grills are just plain quads running a shader that can display a parametrized grid. 

I'll probably drop the AO for a completely flat look, but I guess that'd mostly depend on the gameplay. I had in mind something using shadows... Still contemplating...

Update. I implemented basic door closing/opening and added a simple minimap. I kinda decided on the mechanics. It's simple. You need to close all doors and windows. The game now tracks the progress of that. May add some collectables if there is time. The window layout generation needs some more work. 
I'll likely keep AO. Things are too disorienting without it.

More progress.

I fleshed out mechanics a bit, not all of it is implemented but most is. It's a bit weird and goes as follows:

You're in a building and need to close all windows and doors to beat the game.

You have two depletable resources: soul and waiting time. When soul is exhausted the game is over.

Your soul diminishes by exposure to light. Each room in the building has a certain level of exposure that depends on the total area of room's open windows. When you close all windows in a room, the room becomes harmless.

Some rooms contain a Remnant. A Remnant is visible only if hit by direct light coming in through windows. If you close all windows in a room and a Remnant is in the room, it will instantly drain all of your soul and the game is over. 

You can toggle the waiting mode where time runs faster and window light shifts across the room. This is used to search for a Remnant. Waiting time is a depletable resource.

You can gradually replenish soul by entering waiting mode in a room with all windows and all doors shut.
 

The mechanics are now settled. All things listed in my previous post are implemented. The game is generally functional. You can open/close doors and windows, spot and dissolve remnants, wait for light to shift, replenish soul in closed-off rooms. Winning and losing states are in.

Working on bringing it all together into a somewhat coherent player experience, as much as the short deadline allows for. Menus and other gui stuff is always the most "boring" part but no game can live without them. I added basic configuration options like mouse sensitivity and inversion. There are also some instructions, mostly in the form of contextual hints that appear when the player dies.  

I'm pretty much done with the project. Here's the latest gameplay video. There's no much visual difference but main gameplay elements are more refined. For example the Remnants can only be dissolved by clicking on actually visible parts. There's now also the damage to the player from direct sunlight. The light generally more dangerous but replenish rates are also higher. 

I removed the objective to close all the doors as it seemed a bit tedious. So only windows need to be closed.

The player can escape an encounter with a Remnant in a short period of time while the last window closing animation is playing. In that case the Remnant occupies the room and any subsequent re-entering will instantly kill the player. It's a neat tactical mechanic allowing the player to close the room without inspecting it with light, at the cost of making the room unreachable afterwards. It started as a bug that has grown into a feature :)