Part two- tiny level design

There is something freeing in setting your game in a alien base, goblin fortress or... you know, environment, that doesn't exist in real world. As a developer you can focus on "rule of cool", think about the level as enemy encounter arenas, with interesting sight lines. Most of us never infiltrated an alien base, so nothing feels "off". When trying to create levels based on real spaces, you can sometimes get this dissonance. I know, that the reason Hitman developers put two exits from a bathroom in a suburbian house  is they want you to always have an exit, when trying to escape pursuing enemies. But it looks a bit dumb, and you know it, because... you spent time in houses.

In anomaly search games, it's the other way around.

You NEED to start the player in a familiar environment. I've been in a metro train at least a couple times a week for last twenty years. I wouldn't know if something is wrong in a dwarven mine, but I know it instantly in a space I know from real life.

That's why my game takes place in an apartment. And because I am lazy, and like to take inspiration from my life, the apartment is based on mine. I made some changes, of course. My actual apartment is designed as a place to live for a family, and not a place to search for anomalies for a ghosthunter, after all.

Then, there is less clutter, and overall... stuff. The narrative reason for this is that our protagonist is single. The gameplay reason- that every piece of "stuff" is potentially another anomaly for player to look at, which ups the difficulty level.