They seem pretty bugged to me. I had 15 legions invade a homeworld with only 5 defending and no matter what they'd always beat me back. I tried softening them up with multiple invasions bombarding or poisoning the planet each time instead of doing one big invasion, still lose. It's like the first invasion 99% of the planet dies, and the last 1% becomes Sparta and refuses to die. The blue bar, tech, and numbers are so far in my advantage it shouldn't even be a contest. Eventually I just hit the quick battle button and it somehow decided I'd win.
Later on in the game I got a huge advantage in the invasion bar and the SAME THING is happening.
I recorded it this time to see if I'm doing anything wrong here.
99% of the population dies, then despite me still having a majority of my army left. They stop dying. Continue to kill off my guys as if they turned on some invincibility cheat. And then I randomly "lose" despite still having tons of troops left. I figure, okay... they must've routed. But then they aren't back in space or anything all the legions are lost. So if they're fighting to the death why do they give up fighting halfway through and then magically vanish? Either route and be usable for a second invasion or fight to the last man standing.
Like what is going on with this mechanic? Are you supposed to just invade with like 100+ legions just to get one crummy homeworld that has nothing going for it in a doomed civ? Things used to be a lot more fair in GC2. I could even be outnumbered, but with superior tech still take a win. Please tell me there's a star or planet buster in this game still so I can just skip land invasions entirely. Or a way to just mod out this mechanic to be more fair because it seems very broken and buggy to have an interface tell me one thing and the results be something entirely different.