Alex, would it be possible to add this scenario? ...
Yes, it would.
The way you'd set it up would be with a combination of objectives with the OBJ_Timed success condition, a set of StoryZombieVolumes & Some checkpoint volumes.
Your timed 'wave' objectives would look something like this :
Each time the wave completes you would have another objective, like some sort of down-time followed by another 600 second timed objective. rinse and repeat.
To make the zombies spawns increase with intensity as each wave progresses, you would need to have at least the same number of volumes as there were 'waves'. Each Volume would be configured like this :
In this way the Zombie volume would only start spitting out ZEDs when it is trigggered by the objective. You can use the Objective's 'ActivationEvent' for this purpose. And 'CompletionEvent' to shut the zombie spawning off once the wave is over.
Finally, you would want to checkpoint players as they progressed through the waves to respawn dead ones and save their progress. You can do this using checkpoint volumes. Here's how you might set that up :
In the above example, the checkpoint would be activated when it was triggered (presumably by the Wave objective's 'Completion Event'). You would need one checkpoint volume for each wave. Also - Note that for checkpoint volumes to work they need to have at least one playerstart inside them & the paths in the map must be rebuilt.
If you have any further questions about this setup, I would be happy to answer them in real-time on Skype. It's easier than typing out enormous forum posts
Skype username is A_Jim_Quick