Aight, I played thru, and I noticed.... You have ALOT to work on to make a good map. there were alot of texture-colliding, and you must know this, that walls and walls_extensions without a proper pillar placement between then, will make a hole in the wall, making the player able to see thru. And also, if you did not, try to use BoxLight, PointLight, Spotlights and particles. just those few extra additions in your map makes it look so much better.
If you would like to, I could send u a map that I made, where u can examine how I made different lighting and particles. Just PM me if u want it