LDSF, in case you're wondering, stands for Laser Deployed Security Force. Naturally. And it's great. Pick up some ammo and wonder out into the hanger-type room and, whoa, what was that?! A few seconds later you're shooting frantically and running for the health charger.
Who would have thought to use lasers like that? The great original idea is helped by its cool execution. And of course the lasers look good too. Download this map and have a go!
Oh, and open the RMF up in Hammer as well. 'Nuff said.