So, I think I beat the game.
But I'm not sure...
I attacked the Wargot mothership, fought through it, blew up all 3 strands...and after seeing the ship blow up and hearing the "space horse" theory, the game seemed to keep going.
Has it really finished and is just doing some open-ended "take over the world if you want" thing, or have I missed something...

Nope, that's some flaw of the game. This part badly hint about the continueing. Keep going for some ingame twice days, maybe few more, there will be a new event.
Or, did you patch the game with this recent good 1.3 one? It fixes what could forbid you to have the event.

Alright, I'll have to let things run a little more. I did install 1.3 way back before I started this game, but even if I hadn't, I didn't fail the first Starghost mission, so that shouldn't be a problem. Hopefully I won't have any problems!
Glad to hear there is a bit more to the game...otherwise that would have been a very boring ending...
EDIT: Ah sure enough it seems there is some more going on. Along comes another group to the little party I call Aftershock. I hope they bring something interesting with them, or at least some new tech to research.

The ending is not that worst than Afterlight one. And I think it's really better than Aftermath one.
But it could for sure be better in the whole.
Nope, or very few. What is badly done is that nothing says we can destroy almost all labs and factories, to have Secret Services (put at least TWO in a base) against remaining Cultists, and militias against Starghosts, helping being less bored with the end.
But, I prefer a good long game than a bad short one..