GLaDOS is making new and challenging tests with new elements. As you advance from test chambers, you find out more about yourself and Aperture.
This map is the tutorial level for a Controllable Turret.
(Yes I know, glass isn't there. Still Perfecting a great breakable glass.)
I love the idea of a controllable turret! Why did you use wall textures for the ceiling?
Actually, they're custom ceiling textures. Just made bigger versions, I don't like using too many 32 x 32 squares all the time and I don't like scaling textures to make it bigger.