Being the clever person I am, I started a 7/7 on 10-planet snake with myself at one end... figured I'd slowly bulldoze my way through. Get up to the first homeworld, and after a couple of hours of back-and-forth I'm ready to make my decisive strike... go in, and everything is invincible. It takes me a minute to realize that A- and B-shields are still active, up past that homeworld on other core worlds.
Do I just give up? Without being able to touch guardposts on the homeworld chokepoint, there's no way I can get sufficient forces through that mess to take a core world... and they've got invincible warhead interceptors on the homeworld and next core world, so I can't cheat my way through. I'm stuck.
Heh. I just saw this and was going to say that it's not actually impossible, just a pain in the ass, but then I read down further through the thread and discovered that you already figured it out yourself. My "thing" last month was playing 10-planet maps and deliberately leaving Core Shield Generators on, while also deliberately gimping myself by doing stuff like leaving stuff like Spirecraft off, because I'd been relying so heavily on Martyrs (and bringing it up again because of that helped lead to them finally getting nerfed; you're all welcome).
Depending on the map and how cranky the RNG is feeling that day, it can be kind of painful but doable, or it can be absolutely brutal and borderline impossible. I'm going to guess that you didn't run into the situation in that game that I kept repeatedly getting seeded on my maps that resulted in my inevitable doom most of the time. While any of the CSGs are still intact, you can't damage/destroy any of the structures on the homeworlds, because they provide complete invincibility to them. One of the possible structures that can be seeded on a homeword is a Core Raid Engine, which launches a wave of mk5 ships every four minutes if you have any of your own ships at the homeworld
or any of the neighboring worlds. On a 10-planet map, at least one of the CSGs, if not more, will be seeded on one of the core worlds next door. You cannot damage the CSGs until you control the planet, because they're invincible until then. Going anywhere near the planet with the CSG triggers an endless stream of mk5 ships. You cannot stop the source of the ships until you destroy the CSG. I think one time I went in with as much as
three golems and a nuke on my side and
still eventually lost. FML.
I've seen some particularly evil variations on that, like in one game the planet with the CSG had more than one Warp Counterattack Guardpost on it (under shields, of course) just for fun, along with warhead interceptors and ion cannons and orbital mass drivers and radar jammers, and between the two AIs they just happened to have a fleet ship that could decloak stuff along with having most of the Spire fleet ships, just to be extra dickish. It's like every time you think you might have some suicidal way of dealing with it that has a 1% chance of success, they already have something in place to preemptively stop it. Less evil but still entertaining is when you send a scout through and discover one of those Neinzul guardposts on one of the homeworlds parked right on top of the wormhole, which gets triggered by the dying scout somehow, and 1500 cockroaches come pouring through into your own system a minute later. Hilarity ensues.
And then a few tries later on a new map, it stops being a complete bastard and gives you one that's actually playable, like yours. Heh.