Underrated gem. The puzzles were pretty good. I especially felt satisfied when I finally solved the clock puzzle (I didn't know you could click to open the bottom center part for the longest while lol). Only thing is it's sometimes hard to know what's interactable and what's not. I stumbled upon the fire pit puzzle and solution by complete accident because I was spamming E on stuff.
Game would definitely benefit from sort of minimap. Maybe an inventory item you could open to see which part of the mansion you are in. I was able to navigate pretty easily after some time. But a lot of the hallways felt pretty samey.
Guns trivialize the vampire threat pretty quickly, especially after you find the extra ammo and shotgun. I didn't mind though cause collisions with them were pretty janky. It's easy to get stuck between their arms.
Presentation is definitely going to need a lot of polish before a Steam release. You should try taking queues from VNs for your dialogue ui. Maybe have a dedicated nametag and mini portrait for the characters.