Thanks itchwon86! Really glad that you like it. As for the effect on the screenshots I used a colouring effect called dithering, it lowers the number of colours creating the effect you see on the screenshots. There are a few good tutorials on YouTube on how to achieve this effect, however, I'd also recommend using https://marcis.itch.io/psxfx if you want a faster way of getting the psx feel. Hope this helps :)
Viewing post in Retro PSX Style Mansion Assets comments
I'm not entirely sure, all I can thing of is the lighting, I used a very dim orange light to light up the room and then highlight the specific parts of the room with brighter lights in the candles. Other than that I'm not too sure, but I would highly recommend buying that pack I mentioned as it's definitely worth it if you're into the retro look in my opinion.