I think it's via audio queues, though I'm sure that our developer will be better off answering this question. I technically haven't played seriously yet, though I love the concept!
I just purchased this game, and the moment I read about it on audiogames.net, I was instantly mentally hurled back in time to my Playstation I days ... blasting asteroids is practically all I was good at; that, and fighting games. Love new takes on old games!
