However, I still think there's a problem in there: It looks to me like when any single planet reaches the spawn threshold, any planet that has ever contributed to the spawn pool gets that entire spawn's worth of points applied to it.
Yes, that's exactly what it does
It's not so bad when the base spawn amount and spawn-growth-rate are low enough, but the general idea is that once a spawner is "activated" it's a permanent liability to whoever holds the system (or is nearby). By the same token, activating a bunch of them doesn't dilute the spawns (which would make them far more manageable, can't have that!). The result for cascade-hilarity is quite intentional, though I think I may need to ratchet back on the number of spawners so you're not tripping over them quite so often.
Hmm. It basically guarantees that it's not worth ever trying to hold a Fac IV or Fab in a system that has a DS in it. Because the Vengence shoots plasma shots, not even forcefields will protect your stuff. That certainly changes how the game would be played. Any chance of getting an indicator of some sort when a node is active? maybe have the first kill in a system change it from "Dormant Generator" to "Active Generator".
I can see this becoming a potential strategy - Find a DS system near you, then one deep in AI territory. Activate both, then deliberately kill lots of stuff on your controlled end, and hope that the other end can weaken the AI a lot without going out of control. Hmm. Seems like a desperation strategy, actually. Can we say 10/10 cheese? Yes, we can!
I can also see such a system becoming a Champion Experience Farm.
I'm not sure that there's anything you can do to truly balance an infinitely expanding enemy, but the failing can sure be entertaining. (Why is there no "Shot in the head" smiley?)
No matter what, I suggest making it so that Scouts, drones (Neinzul and tackle), blades, missiles, and disposable stuff like that doesn't cause an increase.
I would also suggest making the DS a seperate not-allied-to-anything factions, so that the Devourer, hostile Gatlings, etc, will fight with them.
Sounds like you didn't create a minor faction, you created a freaking zombie apocalypse.
Actually, that sounds like it might be fun. New AI Type - Zombie Master. Doesn't launch waves, instead it continuously streams zombie ships from the AI homeworld straight to the human homeworld. The never stop, never hesitate, just keep coming... AIP would determine spawn Mk and rate/clump size. For added fun, make all ships spawned this way also become zombie reclaimers