A few years before this game, they launched .fr-08 [1] which was a 64k demo which lasts 11:01 minutes and renders full 3d scenes, with music, animations, models, text, etc. It ranked 1st at the 2000 Assembly (The Party).
As far as I know, they used the technology from .fr-08 for .kkrieger.
[1] - Pouet link: https://www.pouet.net/prod.php?which=1221