The 19th map in the verc's collaborative "Project Quantum Leap" mod/levelpack. The official level name according to the pql site is "mazy's masterful monument", but it was NOt my idea to name it that! (-: ....really....
The setting is black mesa desert warfare, and the combat is quite difficult. I have gotten a lot of flak about how difficult it is, but at least let me say that the mod leaders specifically asked me to make my level quite hard as part of their overall mod vision and protested when i made it easier in a beta.
Anyways, the link is to the entire project quantum leap, which is quite large, and i would recommend it to you as a fun singleplayer diversion.