Interesting no one has commented on this map for almost 2 weeks straight...

When firing up the map, it feels very impressive due the atmoshpere and the fact the textures which are being used are the low-res kind of Sauerbraten. That being said, it obviously is due the details on the map.
You keep discovering new tiny details after every corner.
Although this has a downside on a map like this. After deleting all the tubes, the WTR went down from 199K to 136K. That's still a lot for a Deathmatch map, but a bit more practical (80K or less is considered appropiate troughout that mode).
So I would advice to use a bigger gridsize for the tubes or use something more convenient. Skytexturing surfaces which you can't see from the playing field on any way is another option to get a better performance.
It's not always performance which is the reason to get less WTR on a map; having less of that reduces the amount of lightmaps being generated also (thus a smaller file-size).

The map is flat mirrored, which often doesn't work very well in Deathmatch. Not sure what to think about it, though.

Licensing the map as GNU-GPLv2 is kind of a hassle as Sauerbraten itself (and the content of Sauerbraten) isn't compatible with that license. Taking something like a Creatieve Commons License often has less restrictions.