Hello. I found three videos on the youtube channel
intecrisis called "HL2 Beta Kleiner's Lab" , labelled part i, ii and iii. The videos depict maps running in a seemingly modified retail engine, done in the usual beta-inspired style that combines assets from different development eras, including retail. Here is the first part
The maps were done by Soul of Dark Light. Where can they be found today? I do think that they look quite interesting, for what they are, and I'd like to give them a try.