These four HLDM maps, FloatingPoint, FloatingLine, FloatingSurface and FloatingVolume consitute one of my playground themes for abstract architecture and light experimentation. They all have similarities in texturing (same palette, use of the HL glass textures) but are very different in layout and approach to gameplay. While not the prettiest textured maps ever made, they did help to "free my mind" and some of the ideas have been incorporated successfully into my more "normal" maps.
I have considered taking this theme into the Source engine with its use of lightmap grid and bigger brushwork geometry.