Today I learned how light guns work. Or better: Worked, because these days it’s no more a thing. Light guns were controllers for computers or game consoles. The special thing about them: They looked like a gun and you could just point a the position on the display where you wanted to shoot. But their original technology relied on “Cathode-ray tube” (CTR) based monitors as those would only paint one pixel after another which allowed the light gun to coordinate with the software that was painting, which pixel it was pointed at. These days monitors work fundamentally different and therefore no longer work.
I came across that due to having “Linus Tech Tips” in my RSS feeds and they made a video about it. They go a bit more into detail if you are interested, as well as showing a modern interpretation of the concept.