I had a thought regarding getting Duck Hunt (and other NES light gun games) to work on modern TVs, and I'm here to see if anyone thinks my idea is feasible.
It would require original hardware, rather than an emulator, and a re-programmable NES cartridge (I've seen these available online that connect via USB to upload ROMs.
please forgive me if this idea has glaring holes or has already been though of, as I have next to zero knowledge on the technicalities of ROM hacking. My idea is to modify the Duck Hunt ROM in such a way that would introduce a delay between when the black screen/white target box are displayed, and when the game reads the output from the light sensor in the Zapper.
My understanding of how the Zapper works is upon pressing the trigger, the game turns the screen all black as a means to check whether the user is pointing the gun at the TV. The game then paints the target white to detect a hit. Old analog tube TVs had consistent timing between models and the game was hard coded to that timing. Modern sets have a delay imperceptible to the user but way off to the NES.
Given that each model LCD may have a slightly different delay, the other part of my idea would include some sort of homebrew "game" where the user fires the Zapper at the TV repeatedly until the timing sequence is recognized and the delay can be added to the gun game (picture how Guitar Hero calibration is done, except automated due to the precision required and given the fact Duck Hunt doesn't have a manual calibration mode).
This homebrew calibrator could be a white screen that flashes black upon trigger pull, pulled repeatedly until the black screen is detected. Stage two would be another color, say, blue, that then flashes black followed by white, again adjusting the timing between pulls to set the correct interval between screens. The game can then be modified to delay the screen flashes by the determined period of milliseconds.
This was a lot longer of a write up than it was in my head. I hope it makes sense and I really hope someone out there with more knowledge than I have could attempt it. If you made it this far, thank you!