New Half-Life 2 development lore drop!
It’s a wild ride to read. It’s about a very niche bug that softlocks the game but somehow the bug can travel back in time and even affect the original retail version of Half-Life 2.
TLDR: the bug
The softlock happens because an NPC is standing in the way of a door. This didn’t happen in the original because it was compiled using the old-school Intel x87 floating point handling and not the (relatively) more modern SSE behaviour, which does cause the softlock. The bug managed to time travel to the retail build because modern compilers use SSE instead of x87.
At one point, Valve accidentally broke blinking in HL2 era versions of the Source engine.
Like uh, there was originally, for all humanoid NPCs with visible eyes, some kind of timer and functionality that would cause NPCs to blink, at semi-random, semi-regular intervals.
Somewhere around approximately 2010-12, I think?.. they broke this, and no NPCs would or could blink anymore, outside of totally scripted sequences involving blinking as or eye movement as a deliberate part of some fully blocked out, pre-scripted skit.
… Last I checked, roughly a decade later… they appear to have fixed it.
But I remember this being broken for like, years.