GLaDOS is making new and challenging tests with new elements. As you advance from test chambers, you find out more about yourself and Aperture.
I don't like using BINK in the background for the menu, so I'll use maps like the Orange Box game's menu
(Imagine this as the replacement for the BINK I made for the picture of the menu.)
Overgrown Overgrown.
Would you like some Walls for your Overgrown?