Half-Life Alyx uses the same flickering light code as Quake, from 1996

pcgamesn.com:

Half-Life Alyx, Valve’s groundbreaking 2020 shooter, is a technological wonder – looking at it, it’s hard not to marvel at just how much FPS games have changed. From Wolfenstein to Doom, the first Half-Life to Halo, over the last 30 plus years, we’ve seen myriad PC classics come and go. Nevertheless, their spirits live on. Like a baby born with their great-grandfather’s eyes, it turns out Half-Life Alyx has some specific genetic code in common with its decades old ancestor – the first Quake from 1996. This is an eagle-eyed spot.

The link between the two families – the Quakes and the Alyxes – begins in 1998, with the original Half-Life. As you might recall, the first Half-Life is built using the GoldSource or ‘GoldSrc’ engine, which Valve created using the Quake engine – designed at id Software by John Carmack – as a foundation.

GoldSrc itself has been iterated upon and rebuilt over the years, most famously as the Source engine used in Half-Life 2, and then the Source 2 engine, which powers Half-Life Alyx and the upcoming Counter-Strike 2.

Since remnants of the original Quake engine remained in GoldSrc, and bits of GoldSrc were passed onto Source, and some of Source went into Source 2, there’s a direct codebase lineage between Quake and Alyx. That much you might have already assumed. What you may not have realised is how clearly and specifically you can actually see this link in action.

Set in a partly medieval, partly dystopian industrial complex, the original Quake features a lot of flickering, fluorescent lights. Venturing through the ruined buildings and apartment complexes of Half-Life Alyx’s City 17, again, the player naturally witnesses a lot of light flickering.

And here’s the thing: the way the lights flicker,