Really nice one. There are issues as others have mentioned, like the gameplay being a bit one tone, while still being fun tho, and the somewhat copy paste feeling hallways in places.
In terms of atmosphere and style this one is off the charts. I am not usually a big fan of the Quake 3 textures, but the way they were used here is very well done. It also gave me Jean-Pierre Jeunet vibes (esp City of Lost Children), albeit a bit more metal, what with the skulls and such, with a bit of Shiny circa MDK/Messiah thrown in, which vibes wise is a plus in my book.
Also very unique, esp for Quake. Really loved the rickety looking walkways and deep chasms. Very oppressive.
Another slight crit would be that it seems the map is not vis'd and it is possible to see the void at some point when looking up, which breaks the immersion a bit, if void color is set to default (or anything non black.)
Looking forward to more maps from you and strongly agree with Fairweather regarding an M2 to this