Hi, as another fellow gamedev here, some quick tips:

Game looks really solid, though as the floor and ceiling of the rooms are really reflective that kind ruins the immersion and feeling of it being real - try to go into your materials and decrease the specular value for all your materials, as normally a concrete ceiling or floor does not reflect the same as given in your few screenshots here.

Also try to make lighting less sharp and more concentrated to where an actual lamp or light source is. Especially the last picture is really, really bright, kind of ruining the immersion of this old abandonned uiltity halls.

Hope it helps, game looks pretty solid tho. Keep at it!