Ongoing story arc? No; can't say it's been explained, although I've popped in from time to time since the thread started.
We built the castle when we had to do extensive repairs after Staggy rode his pet T-Rex through the back wall of the Smoky Backroom. Twice.
It just grew from there. Bob has been so good about making a "habitat" for us...kitchens, bars and gym are open 24/7 as is the library and the observatory. The library has a fireplace, furs and eats from the kitchen. The observatory has furs and eats from the kitchen.
We have a moat, a hunting preserve, orchards, and I guess anything your little heart desires....KP did the graphics for it, once upon a time...we even made a test beer run to Scotland.
I know I've forgotten a lot of stuff, but I'm sure someone will add the rest of it...
Oh, drats.
Okers.
Well, ,there's a sectional story, posted in bits and pieces throughout the thread, er, series.
One day in the initial run of the undead thread on the very bones of jj_fate, we all said, "Hey, we can build a castle!"
And so in text form, a castle was built.
And then we said decided to be mobile.
(A mobile castle? Sure!)
So in text form, the castle has been retooled *cough* to be a huge space going vessel.
(Destination: Mars. Gotta moon the Viking Probe..)