Hey there.
I’ve tinkered with procedural random level generation topics for years and eventually gave up a long time ago. I had focused on HL2 and just couldn’t get anything done that looks halfway okay with its assets. No matter what I did, it just looked dirty.
Then Black Mesa came along, with its beautiful assets, better gameplay, much cleaner textures and friendlier colors… and my motivation was refreshed.
After almost two years of work now, I’ve successfully generated a pack of 10 playable deathmatch levels today that I just wanted to show here too. 
These two are from the same level layout, but with two different themes and different loadouts for the items: [edit: as a new user, I can only post one image]
We’ve playtested a bit today, and the “maze” layout turned out to be the most fun so far.
Again, two themes, two loadouts (one foucuses on bullet weapons, the other one has more weapons available): [edit]
My first level layout for this technology was a rather complex one.
Here are a screenshot from a variant with less room, and one with more room.
[edit]
Another layout, another level - This one features a big central occluding column and pathways leading to it: [edit]
And finally, I also have an outdoor level. For this especially, I’ve taught my program how to work with skies and grass:
I’ve posted about the development work so far in this thread on facepunch: https://forum.facepunch.com/dev/uroy/I-like-level-generation/
And the levels can be found in a download in this post: https://forum.facepunch.com/dev/btaas/The-Official-Facepunch-Mapping-WiP-Thread-v18-Source-Engine-and-Friends/29/#postcwysia
If any of the BM devs reads this: Thank you for this awesome game! 