Ok, it's not defender. I wish I could remember more. All I remember is playing it on a old Mac. I remember driving a purple or yellow box car like thing. I think you shot at something. I remember floor looking like a black grid with a dark to lightish purple background sky or something. There were funny shapes, and now and then a guy's voice would say something. It was hard to understand. He said something like "over here" or something like that.