@davidrevoy It worked by displaying a single white screen for calibration when you pulled the trigger, then a black screen with the targets as white squares. The NES would know which target you hit by counting the time it took to build up the crt lines of the target.
In a nutshell, it's impossible to play on lcd/led screen, and probably too with an emulator. Maybe an old RPi with an RCA RGB-out might work, but I don't know.