A quick post to add the following thing :
A training video from another guy on LMS, all stages exept 2 it's missing. If you want to make an idea of this ultra epic map (but a little gliched)
Stage 1 :
Stage 3 :
Stage 4 :
Stage 5 :
As you can see it has multiples things to to in the map to achieve it + a really team work (when others are defending, some players have to stay triggering and tell other when it's open because no console alert)
There is some items and vehicles to control (apache, tank, exosqueleton, soldiers to place on battleground (stage 5 video).
Boss is really epic, and the end too
+
http://zombieescape.wikia.com/wiki/Ze_Last_Man_Standing
Enjoy