I got back to working on Shoe String Shooter, a PC game using DirectX11.
I was testing gameplay with flash lights. The reason behind it is that flash light allow you to see to a longer distance but they also reveal your position. Another possibility is that the flash light is going to blind your enemy if he looks into it directly.
Another reason is probably that I would like to fiddle with making better lighting for my game.
In the meantime, here is a youtube video demonstrating flash lights in multiplayer.