40k/Dune/Star Wars, mind. That leaves room for light space magic/pyskers, as well as for proper artificial planetoid-scale megaprojects, although those'd be either yet to have been made or been put out of commission. I would not put it past War of the Worlds Martians to try and replace the planet's dead, mined-out core and make some kind of crudely unsubtle fusion reactor, a contained artificial star, to power an entire mechanized undercontinent beneath the planet's crust. Like a tiny Dyson sphere. I would also not put it past them to fuck it up and, instead of producing a stable fusion reaction they could harvest more energy from than they needed to spend to contain it, cause the entire planet to go up like Alderaan by making a pure fusion weapon the size of a tiny moon, causing immense damage to Earth. That'd leave the Martians with only any exterior population to work with on the other dead rocks and the asteroid belt, though, so one would have to work out how they'd have garnered enough numbers after waking up or while still in-transit stasis to pose a credible threat. Automated cloning, maybe, tubescum kids that never knew home. What do you think, Willy? Any of this spitballing sound like it's on the mark?