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

Half-Life Alyx is a groundbreaking FPS game, with Valve’s VR tech bringing City 17 to vivid life, but the shooter hides a neat code memento from Quake.

Half-Life Alyx uses the same flickering light code as Quake, from 1996: A soldier in green armour from the 1996 FPS game Quake battles a monster

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, the pattern that they’re coded to follow, is exactly the same in both Quake, from 1996, and Half-Life Alyx, from 2020. You can see it below, thanks to the extremely meticulous detective work of Twitter user ‘JoeyCheerio.’

This is all down to a line of code named ‘fluorescent flicker pattern 10,’ which existed in Quake, was inherited into GoldSrc, and so on and so on, until it appeared in Source 2 and Half-Life Alyx. Incredible, right? So, you see, though technology in gaming may move fast, the history of FPS games remains very much alive.

Big Quake and Half-Life fan? Check out some of the other best old games that you can still run on your PC. You can also take the best VR games for a spin.