Imagine your going about your daily life & the world you know erupts in nuclear fire. Your descendants awaken in a new universe inhabited by mutants & monsters!
The idea of one of the ships of the Warden crashing into Earth & causing the meltdown of civilization as alien creatures are dumped on Earth isn't a new one. I can totally see using various Castles & Crusades material for this. This small side ship of the Warden's mission slams into the Earth & sets off World War III. The Earth is perfectly suited for a mutant & alien creature hoe down.America & Russia nuke the heck out of each other as they mistake the crash for a provocation to war. The Siege engine setting rules in the back of the Castle Keeper's Guide are geared for a sci fi setting.
So its really not a hard stretch at all to be using this book to run Gary Gygax's S3 Expedition to the Barrier Peaks with Castles & Crusades. Especially if the dungeon master was to take the adventure & pair it with the recent Kickstarter. This Warden is another 'runner' ship for the larger vessel that's still up in orbit & it's computer banks thinks its home! The fact of the matter is that the DM could plug this idea in & run with it using various Metamorphis Alpha resources especially the Goodman Games Original Adventures Reincarnated #3: Expedition to the Barrier Peaks.