I like Mika's Games! My favorite part was turning off the alarm!
Really nice looking game.
The interaction prompts (for opening doors etc) were also super nice. Having them appear in the world (rather than just a hud notification or something) feels really intuitive and pleasant. I'm surprised I haven't seen this in more games, given how natural it all feels.
The mansion looks really good, and exploring it, while avoiding the ghost feels good. Damn though, soo many places to search.
I'd maybe like to see something to help narrow down where the key is. Like maybe you have something you can check periodically and it gives you a warm vs cold readout so you can use it to roughly work out what area it might be in. Maybe you can only check it every 30/60 seconds or so, or they're single-use items you have to find in the mansion and spend to help narrow down the key (maybe like, some special candles you find hidden throughout, and if you light the candle in a spot it somehow gives you a readout - something like that?). As it stands it's super hard, and I think there's probably too many places to search without some kind of help. To maybe introduce more complexity and risk, maybe every time you use this thing it spawns in an extra spirit? So it helps but also increases risk, especially if you don't use them in good spots.
(sorry if that's all obvious, I see in your TODOs now you wanna get in some helping items and stuff)
Cool idea, and well presented game!