Ghost of the Mystery Maze - Harry Potter Inspired

This is one of my earliest trials with Unity(back in 2021), where I created this 3D model in Blender with the help of a few assets from the internet, but mostly self-made. But instead of having the model's files as individual meshes, I joined all the meshes, resulting in one big polygon with a huge number of triangles. This resulted in a failed deployment of "Mesh Collider" in Unity, thus the MC can pass through the 3D objects. Therefore, this walkthrough is more from a ghost perspective, and I am working around a narrative to fit this.
Inside Unity, I added some ground planes for the MC to walk through without going through the meshes, and did a lot of work on the lighting part. I could not bring the moody fog effect from blender to unity, as well as many of the emissive materials for objects as I joined all the objects together.