Cool, that looks like it would be more challenging and exciting than normal outdoor battles. I know it can't be done anytime soon, but it would be awesome to have a paintball fight inside an office building or hotel or some sort of complex that makes you feel like you're in the movie Die Hard or something.
its cement painted with, what i was last told, walnut crumbs mixed. they tried a sand paint but that got slick fast. it used to be a ton of astro turf but that got slick fast too. its actually not too bad when they actually get around to washing it (once a week). i know because i've been there to wash it.