Pretty intense. I plugged in Psychotic's save and have been having fun safely expanding out. I turned the ridge in the southeast into two hill forts with sheer cliffs, I dug the river out to flow into a moat which now surrounds the intramuros, and I sit upon a horde of crossbows and bolts. Maybe I will play Demon Dude's save since it sounds interesting.
Edit:
Please note your original plug at the bottom of the moat was also made of ice. And your original ramp into the fortress? Built into ice, so I can see why the initial "flood" happened.