Valve has been using exactly the same flickering effect for over 25 years
The flickering light effect was likely written by none other than John Carmack for “Quake” in 1996. That was part of a library of flickering presets compiled by John Romero in 1993 while working on “DoomED”:
Every time I see a game use the Quake light flicker code I get a warm glow.
TIL this is a thing
neat.