Nostalgia is a funny thing. If you experienced the early days of video games in the 1980s and 90s, there’s a good chance you remember those games looking a whole lot better than they actually…
I would expect hackaday to go into more detail. Ironic.
It looks like all they did was uncap the render distance, to let the game render the high detail level at ranges that would have crippled the original hardware. They didn't actually hack higher quality resources into the game. Same resources, just all on screen at once.
A shame that all the really early 3D games use their own software rendering engines, and aren't so amenable to being "cranked up" like later games when accelerators became common.
Get some of the early freescape games like Total Eclipse or Castle Master, early cyberpunk games like Interphase, or even Frontier: Elite II running in big resolutions with silky framerates and insane draw distances, I'd be so pleased.