It's one of those things that you just have to play to get it. It doesn't just throw you around, you have grapple and you can run on walls but only for a few steps, etc. It all works together to let you do some interesting things, but guys like this that just have an intuitive understanding of it can dome really insane things.

It's not just another FPS. The movement is the central mechanism of the game and the maps are designed around it.