The map is Turbine, rotated 180 degrees; with some ramp additions and minor editing to make the map work.
As the teleporters continued to spew out bread, the gravity polarity of the earth was changed. The ceiling was now the floor. Anything outside was flung into space. The mercs did their best to try to re-set up the buildings so they could continue to fight. Bless their little hearts. Anything bolted down would stay bolted to the now ceiling. Anything else... well they cleaned up the best they could. They had some killing to get to.
The Steam Workshop page for the map
Not sure if it's a map that's actually fun to play outside of the novelty of the context. It seems easier to cap, so defense is more important than the normal version. Some folks get a mild vertigo when playing.
It's more or less done unless something unexpected happens with it.