Yep. You can use the gameport or a gamepad for just about any basic input, but I wouldn't suggest it for output of any kind or an accurate analog input. It's quite susceptible to RFI. For 12V detection I use a resistor and transistor, and for buttons it's just direct. I wouldn't use a photo resistor for dimming the screen, but all you need to do is calibrate by holding your finger over it and shining a light at it to get a good range. For dimming, what I have is a connection to the instrument panel dimmer that came off the HU connector. Here's a pic of what it looked like at first. Jjust think of it as a normally closed relay because it's kinda backward, and that white thing is a 2-pin connector to the dimmer line. Without power to the relay, the backlight inverter is powered by the lilliput, and when the lights are on they power the backlight through the 33 ohm resistor.