Random thought: Capture data centers rather then kill them allows them to slowly generate "defensive knowledge" over time. Either that or a new form of capture-able item would work, which would probably be a better idea since most data centers are near the end of the game, not the beginning, so near the end-game it's going to be a non-decision to take them out. They'd have the same effect as the advanced factories then, they're immobile so you have to setup defenses in the world; and probably the computer won't like that so much, so they'll be a small-but-non-zero penalty for this (like the homeworder's human planets, but not quite as harsh 
).
This could be interesting, but I agree that it should be something other than data centers that you capture and use this way -- some sort of new ship.
Maybe a benefit of the human worlds for things like the entrenched homeworlder to make it less obnoxious?
After all you're getting a significant inflow of extra ships, the trade off being you get extra defense.
It also means you can scatter more of these around a normal game, since I only think I've encountered them with that AI.
I wouldn't really want to give them regen, really this sort of thing is what engineers are for. Plus this is one way to force more of the Tech I and II engineers off the battlefield, where the Tech III ones are supposed to shine anyway.
Well, that's true -- but it presupposes that everyone wants (and has the knowledge to) unlock higher level engineers. With increased offensive attacks from the AI, this would pretty much be required. And you'd always have this one weak point in your armor -- the engineers -- that if the AI happens to pick them off, then your defenses will crumble under the ongoing waves to your planets. That requires a degree of maintenance that people tend to complain about.
The idea of given the turrets regen is to make them MORE effective than regular ships at wormhole defense (thus giving a better reason to use them), and also to make it so that the higher-level engineers are not required. I can see your point, but I think that this is kind of a fitting change. Basically, most of the defensive stuff would then be non-repairable but would have regen. Turrets would have a pretty quick regen, compared to say force fields, to make it so that they have to be really overmastered before they die.
It wouldn't necessarily require them to upgrade more engineers. 33 normal ones really are enough to stick one engineer per planet each game. It just means that you actually have a decision, you can make sure each of your defense emplacements has at least one engineer to repair everything up between waves, or you can cope without the repairing around the place in trade off for having a large force of engineers to quickly repair your fleet, or you can buy the higher level engineers and get the best of both worlds.
With auto-repairing it removes a tactical descision for me. Do I put a heavy defense on a wormhole, or a light defense with repairers? With auto repairers I have no choice, I have to plunk down a heavy defense under the assumption that waves will arrive quick enough that things won't repair in time. With repairers I can put down a lighter defense, yet have a much quicker repair turn around between waves.
Also if there are, say 3 wormholes with defense turrets in a planet, do I just have a single slow repairer set to auto trundling around the planet so slow but cost efficient? Do I have multiple, one on each wormhole in case I get lots of attacks in quick succession and my engineer doesn't arrive in time? Or do I buy tech II and get teleporting ones and station one there (rather then dragging them into battle) so things can happen much quicker?
Also if you're wanting defense to suck up ships, as well as turrets, you have the issue you need to repair the ships after every few waves as well, and currently the repair ships are both few and slow, and you would also need to research them as well, and they cost much more then the first upgrade of engineers.
So either way you're looking at "needing" to upgrade engineers, or plunk down a space dock in each planet with a contested wormhole and then have to micro building stuff to make sure your forces are usually at optimal level.
Right, which is why you need more enemies pounding at the door to compensate.
Oh, absolutely. But then that's why you need turrets with better health and regen.
Health, yes; shields, yes; still not convinced on the regen bit though.
Granted I've never setup a serious set of static defenses for most, but the last game where I had serious defenses on an 8x special forces AI world, it's 150-ish ships every five minutes or so could really not be defended against in the long term at all despite using every mine I had, mine-layers, all my force fields to protect my turrets, and a couple of hundred ships.
I've used mines and turrets to exclusively defend wormholes before (and do so every so often still). In my alpha group, we create a little pattern that we call the "ring of death" and it works super well for everything that isn't tractor-immune or able to pass over mines (so, raider AI types are basically immune to the rings of death).
This particular game they popped out of the wormhole and ran straight for my command center of that world, so I had a string of mines three or four wide from the wormhole to my command center, then had a chokepoint with turrets and forcefields and tractor beams and the like half way down it to try and pick things off that weren't destroyed by the mines, if that failed or there were too many to be caught by the tractor beams the rest of the mines should have finished them off. Main problem seemed to be keeping my mine layers un-dead. An upgraded version of the with cloaking would be nice, or teleporting, or both.
One thing I forgot to mention in the last set of verbiage is that we now no-longer have "System Defense Boats", ships that can't leave the system but are good for defense. Teleporting things used to be that spot (and especially teleporting engineers which were perfect for this support role), but they were a bit on the hard to use side. If there was a ship type that was mobile, but could only move between non-contested worlds (that is friendly worlds with command centers on them), it would be the "can't attack an enemy world easy, but is useful for defense" that the original teleporting ships were good for, but without their inconveneince of having to build them on the same planet.
Could be... I'm more thinking that the benefit of defensive-only ships is to be stronger and basically immobile, though. I'd leave this as a secondary discussion for after the other changes are in place, since then we would have a better understanding of what it looks like.
The difference is it's a trade off in the middle. Offense is mobile, but less hurty (they have engines so have less space for guns), defense is immobile, but more hurty (not having to move around means they can mount more of and heavy armament, and heavier armour), the SDB's are semi-mobile but can't travel between worlds, and have less hurty then the static emplacements (they sacrifice the wormhole drive for bigger normal-movement engines or teleporting so they can zip around the system easier).
Yeah, too much playing Traveller in my youth.
