I am incredibly impressed by the number of maps. I played for about half an hour, and I didn't notice any repeats. It was rather interesting really, because some of the maps were open, and others had tight corridors, and others had you weaving round the place, and alot had places that enemies ambushed you. I still don't understand what triggers the 'survive' phase or if that is random or if there is waves, but it ended up being a very fun experience!