What Exactly is Precomputed Visibility Vol and How to use It?

Hey Guys,
I’ve been working on a top down strategy game for mobile devices. And I’ve been looking for options to optimize my scene in whatever way possible before moving onto the profiling stage, as it seems that my game is bound by GPU at the moment.

I’ve looked at Precomputed Visibility Volume, and the documentation says that it is used for optimization purpose and this answerhub thread has an answer which also suggests that it is good for mobile games. It also links to a UDK video which shows its use in Epic Citadel.

Also tried looking into the content example project. But there is nothing to show for it.

I got what it does. But I don’t exactly know how to use it in my project.
Is it only good for FPS and TPS?
Can I use it in a top down game?

Please Help. Thank You