The one thing that's bugging me about this campaign is that
It is set hundreds to thousands of years from now
(around the same timeframe to that of the 2018 film Mortal Engines), where some future alien species came upon our ruins to indulge in the fiction of their own immortality until the Shivans came for them.
is a pretty cool idea that could be turned into a truly epic campaign if done right. Just that this story is not even trying to be something original but just a mesh-up of various already existing things. I thought about similar things in the past, and wished that I could make them reality but well..
@Nightmare's right: Setting hundreds and thousands of years into the future of FreeSpace is a pretty cool idea, given that it's meant to follow Blue Planet as a epilogue to the FreeSpace saga, and that the Shivans are a playable faction. I know I am well aware that this story isn't trying to be something original but, just a mesh-up of various already existing things, such as the UIMS (Unknown Intellectual Mechanized Species, descended from the Cylons from the re-imagined Battlestar Galactica), the Battura, Bosconians and Sadeen, as well as the now-desolate Earth, where the 2018 film Mortal Engines take place around the same time. These said races, based on the counterparts from the United Galaxy Space Force (namely Galaxian 3, Starblade and Star Ixiom) are among the candidates for a future species that was said to have come upon our ruins to indulge in the fiction of their own immortality until the Shivans came for them.
As for whether it serves as a stealth sequel to Mortal Engines, that may be the case. Think of this (along with Blue Planet before it) as a dry run before I embark on such projects, whether a standalone mod or not, which is a purely stealth sequel with canon welding of any kind. Perhaps one day I could create one, one that serves as a stealth sequel to Ender's Game, a 2013 film adaptation of the novel of the same name, itself one of the influences behind the original FreeSpace game.
If I want to turn this into a truly epic campaign that works very well even with new players unfamiliar to the FreeSpace saga and space combat simulators in general, I avoid mentioning what happened in Mortal Engines. Any mentions of the UIMS, Battura, Bosconian and Sadeen are ignored.