The NES Zapper light gun was designed by Gunpei Yokoi and Masayuki Uemura (who also designed the GameBoy and NES respectively).
The laughing dog was ranked No.7 in 1Up’s ‘Top 10 Video Game Dogs’ list and praised for ‘laughing at a frustrated human with a loaded rifle’.
The Zapper doesn’t work with modern TVs which is why we have a Cathode Ray Tube TV.
When you fire the gun, the screen will go black for a frame or two, and the duck will turn into a white square. The zapper can detect the light from white square if you’re aiming correctly, and you’ll score points in the game.
You can watch this video for a full account of how the Zapper works!