I don't know if this is the proper forum for asking for gameplay tips and apologise for the upcoming wall of text but I'm rather desperate at this point.
I've built a fortress in a (I thought) peaceful region somewhere at the edge of a mountain ridge with plenty of wood and game on top and some very rich iron/coal veins underneath.
Sounds like a perfect spot for a mountain hall to spend a long and alcohol fuelled life in but there is a small catch: approximately one to two times a year there are these massive zombie attacks during which the area gets overrun by hordes of undead creatures and necromancers intend on eating everyone's brains.
I've tried:
isolation: building bridges and walls to keep out of their reach helps but it does not solve the problem because the undead kill all the wildlife and any caravans and the undead raised from their corpses linger around after the official siege is ended (approximately 100 - 200 zombies every year and rising since I can't remove all the bodies in time before the next raid).
cage traps: effective to catch the first twenty zombies barging in, but the twenty-first tends to be an undead yak bull or elephant who then leasurely slaughters your dwarf population.
Also my mechanics would try to reload them, invariably getting themselves killed.
atom crushers: I've built an automated atom crusher with a "timer" (a goblin running around in a corridor with pressure pads) but after I got rid of all the necromancers the remaining undead won't attack the fortress and just linger around on the map killing migrants.
the bridge of death: a small bridge across a chasm with tons of weapon traps on it seems the best solution so far backed by cage traps but then suddenly about 30 of my dwarfs decide they should hold this terribly important meeting and where better to discuss things than on a picnic outside the "green zone" burrow in the middle of a zombie infested wasteland
!
That last thing (and the resulting tantrum spiral) brought fortress population down from about 60 to 2 (one is mad and I'm pretty sure the other is a vampire) in two minutes.
It seems the end is near but I've had variations on this scenario several times during this playthrough now and I'm not willing to give up yet but I can't progress far enough to get a descent militia or trap system going before the next attack (even cleaning the corpses would help a lot, especially since the fortress currently harbours more ghosts than dwarfs).
My fortress now undergoes these periodic near-extinctions.
This has been one of the most interesting and hilarious fortresses I've played yet but I have no clue how to progress at his point or to break the cycle.
Any help tips would be greatly appreciated.
