Another (somewhat) technical reply (and I've written plenty of code for the Dreamcast
) follows...Devices that plug into the Dreamcast's controller ports (and any slots on those controllers) can identify as one or more fixed device types. Each device type has various commands that the system can send it that it will respond to in a very specific manner. Just as an example, official VMUs (with screens) report to the system as supporting three types of devices: a memory card, a clock, and an LCD. The light gun also reports as multiple devices -- a standard controller and a light gun. As you have said, you can use the D-Pad and buttons on the gun as they were designed to work, and as they'd work in any other non-gun supporting game. However, pointing the gun at the screen doesn't serve to aim the gun as it should. That's where the earlier description of things comes in.
You don't need to point the gun at the screen to hit the start button or use the D-Pad. There's nothing for the TV to do with that -- it works just as any other controller, just with a more limited set of inputs. Aiming does not and will not work. The trigger on the gun is just another button. The console might react in a certain way (flashing the screen) when that trigger is pulled, but it doesn't mean it's getting any aiming information from the gun. It's getting it from where you aimed with the D-Pad, and acting as if the gun was pointing completely away from the screen. No light gun will ever work with an LCD/LED TV unless it is designed for that (i.e, actually uses image processing to figure out where on the screen it's pointed or uses an approach like the Wii remote). Standard light guns that rely on the electron beam sweep of the horizontal/vertical refresh of a CRT TV will never work, and buying more will not change that at all.
