Destroy super-fortresses?

[Quitch]

It's a secondary objective, but what do I get out of it? There's nothing on the tooltip.

[x4000]

That's a good point.  You get the planet that it is defending, and that's basically it.  These ships can be huge blockers to your plans, or can prevent you from taking an otherwise valuable planet, so that's really the benefit.  Since it is a secondary objective, perhaps I should also make it reduce the AI Progress slightly, though.  Maybe 2, as with a datacenter.  I think I'll add that to my list...

[Quitch]

Maybe instead of making them incredibly tough data centres, reward me with a new ship type?

[x4000]

Hmm... they really aren't meant to be a reward in the first place.  They are meant to be a blockade.  If you want to go around, fine, otherwise they are the guardian you have to go through.  You're right, now I'm rethinking adding AI progress, though.  I think that's just it, they are guardians and that's that.  They probably shouldn't show up as secondary objectives, but I had at once point decided to put all superweapons as secondary objectives for destruction.  That's more in keeping with the other superweapons currently in the game.

[Quitch]

And they're scary. I engaged with 128 bombers, MkII and MkIII to see how it went. Pffft, it barely even noticed me

[x4000]

Oh yeah, it takes 200ish Mark III and IVs, and then loads of time.  They can be brought down, but the effort expenditure makes it hard -- hence making them a more effective blockade.