So I have been working on a project lately, I am recreating the L4D No Mercy rooftop level. I'm not copying or pasting anything or porting any content, it's all done from scratch. I have plans to make several maps out of it: zm, dm, de, and scoutzknivez. I still have to work on the lighting a lot, add cubemaps, adjust the lightning and thunder until I'm satisfied with them, and add some minor touches. The zm version of the map is probably the last one I'll do since I'll have to make quite a few changes to make it compatible for zm, and also I plan to add a helicopter that goes around the map. It's already about as optimized as it can be, since I cheated and looked at how valve optimized their version Here is the map as just a young fetus: I'm keeping the progress of this map updated here and am also considering requests for making it compatible with other game modes.