Random, apropos of nothing:

Bauknecht-Trocken (2005) https://www.youtube.com/watch?v=D8ozOOL-Lxw

You kind of have to know the conventions of demos in general and at the time etc, buuut

The breakdown 2:50 min in with the three paintings by Nero has been living rent-free in my head for over 20 years now, especially that third one with the lingering zoom-in.

Just haunting. 10/10 moment

Trocken - Bauknecht

YouTube

More impromptu demoshow:

Satori-Metamorf (2000)
https://www.youtube.com/watch?v=ex-NaV3w5Ro

Metamorf [Full HD] by Zden / Satori (SK) & Raiden / Aural Planet (PL) [2000]

YouTube

This one is really well known (in the demoscene anyway), but has aged shockingly well:

Blasphemy-moralhardcandy (1999)
https://www.youtube.com/watch?v=1Wsr_oCzlZA

This was "high-res" (640x480) at the time. Most DOS demos were still habitually 320x200 or 320x240.

The textured 3D scenes have aged the most, but even 25 years later I have no idea what some of these effects actually do or how they manage to look so good.

Moral Hard Candy by Blasphemy (pc demo)

YouTube
@rygorous Love the design of the Blasphemy and Fudge prods from that era.
@pervognsen Purple too!
@rygorous Just rewatched kkowboy and I think this is the only effect that doesn't hold up in the whole demo and I remember it being a sore point at the time too.
@pervognsen agreed on both points!
@rygorous Looking at the kkowballs with the way it 'fades out' for lack of a better term, is it doing "marching lines" on the isosurface?
@pervognsen marching squares on every slice I believe, yeah