That’s pretty impressive. It actually does look like an N64 game from the 90s. I wonder if there’s some alternate timeline where this was Valve’s first game and the PC version is the remaster.
The alternate timeline would have to be pretty wacky, a lot of his techniques are using modern software development progression. Sure, the N64 was a limited platform, but also they didn't have efficient and optimized algorithms back then that enabled this type of performance on lesser hardware. That came with decades of experience writing code like this.
Ehhh. The N64 could definitely have handled rasterizing some boxy rooms with repeating monochrome textures and vertex lighting. The voice acting would be unlikely for the sake of ROM cost, especially in multiple languages. But most areas that really tax the system's performance would simply be designed more... simply... to lower polycount and minimize overdraw. You'd see more ramps and fewer staircases.
A contemporary game would have also leaned on all the gimmicks Mario 64 and Turok showed off. The gun would have environment-mapped reflections on its big curved sections. Deadly floor goop would undulate, or at least have an oily sheen across its flat surface.
Here is an alternative Piped link(s):
https://piped.video/nT0Z_M-fJyM?si=nTlRVyupVJZM15qF
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.
