What about something simpler, like having a slew of cade area's around the map but the core is a maze that has walls on timer? There's some sort of random number picked at the start of each round that the timed walls use to decide if they're open, when they'll open or close again.
One cade could be a tower, where you can look down on the maze to watch for zombies (shoot them off the ladder when they come). Other rooms are typical cade rooms of various configurations with a display showing the timing. So if a cade fails, people inside could always knock down the part of the cade away from the zombies and use the maze timing to escape the zombies (could even avoid a fast zombie if you get them blocked behind you). You could even have short passages like vents that people could hold up in or use to avoid certain sections of moving walls.
Anyway, mazes are pretty standard on escape maps to throw players for a loop but most are static. Something that's not so dependable could add some excitement or an advantage to the humans.
Take it to another level and maybe throw in pods like boat escape to hover over the maze and fire down or guns for those towers to fire down or takeout pods, and you'd have one epic battlefield.