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.