The problem is that no one owns a light gun for the PC, so there is no reason to develop a game for it, and since there are no games for it almost no one is going to buy a PC light gun. Some of my favorite arcade games growing up were cheyenne, duck hunt, and virtua cop, but games like that don't have enough depth to compel someone to purchase both hardware and software to play it. If you want to play modern aim and shoot games stick with a console.