Ok, done, in a matter of speaking.
MapSaveI did not complete my plan. It's close, but it's a mess. I didn't have time to restart the rivers, clean up the 70,000 stone that I excavated, and finish up the little odds and ends by the deadline. I did play the map out until it was a proper state which was mid-spring 1006. That map was also uploaded. I don't expect it to be judged based on that, but I really have to finish what I start, so there you have it.
I thought a regular bridge and underground fortress was too obvious for a challenge competition, and decided to try a massive excavation. The other benefit was to bring the river into reach so that a dock/water trade scenario would be plausible (though someone else made a much better ship than mine). Rather than do something really spectacular and detailed, I went for the appearance of a traditional fortress, defensible as such, with a not-too-overwhelming construction. I like very clean, realistic maps, and detest strip mining and things like that. There's no excavation not used in some way. The sides are natural looking and are impassible to invaders except where designed with no loose rock left on the shores. It's the kind of place I would expect someone to be happy living.
I didn't really consider any of the judging criteria. My fortress wealth is embarrassingly low (everyone has been hauling rock, not doing anything to generate wealth), and I don't think anything here it terribly innovative, but I had hoped that aesthetically it would be unique among the contestants. Mostly I needed a building exercise after watching Morul bash the crap out of orcs for 2 months.
Things I was poorly prepared for:
1) I've been playing immigrant only fortresses for a year, and I forgot how quickly the population can skyrocket. I never planned the fortress to hold 130.
2) Lack of magma. I never play without magma and I struggled to reset my thinking around it.
3) Damming a large river. I actually had to fire up another large river map that someone posted a few months ago and practice damming that since I've tried doing it in the past and failed every time. Even so, it took me 5 attempts to work out how to deal with the particulars of water pathing. By the time I got my confidence to try it, I didn't have quite enough time to get it implemented.
Other things that happened:
Sieges started showing up in early 1004. The first siege was on the north side right after I started digging and there were NO defenses set up. I drafted all the miners and they wiped out two full squads without taking a single injury. Lucky doesn't even begin to describe it. The humans decided to siege as well, and got splattered on the outer traps. Another gobbo siege had the same effect. There's a caged bronze collossus on the roof that wandered into one of my cage traps.
Things I'm ready for in the next challenge:
I've got a much better sense of what 5 years can bring. Morul's fortress is in year 45 or so, and most of my others are 1-2 generations in. 20 years is nothing for me, I'm very patient, and 5 years is like a sprint. I've got a better sense of it now. 2 weeks is a good stretch of time. Even with that I was able to take a 3-4 day detour to figure out large river damming.
Bring on the next challenge!