One time I decided to build a pit/drowning trap (first they would fall, then I would pump water in to drown the survivors, then retract another bridge to drop it all one z-level down to the sealed off drainage/item retrieval room linked to the maps edge.).
Being my first attempt at such a trap, there where many flaws (mostly I misunderstood water flow and pressure, causing the water to take too long to fill up).
I realized that I had accidentally made drawbridges instead of retractable bridges, so ordered them to be deconstructed. my mason/miners, taking break from their long trip through the caverns (still no adorable plump helmet men,
), went to work post haste.
Unfortunately, the dwarves succeeded in their task right as urist mcfisherdwarve/corpse hauler was passing the bridge. He plummeted down 4/5 levels, narrowly missing the spikes at the bottom, and survived (he was barely bruised, I'll have to make the pit deeper next time). Unfortunately, the water was already filling at its sluggish speed, and it was too late to free him without causing a flood to my poorly designed fort (doesn't help that I forgot to include an off switch for the flooding part). So I thought, "sure, why not let him drown, see how long it takes to kill him, could be good for a laugh".
He died of hunger
.
Then the real problems began. You see, this fort of mine lacked a fishing industry, and I went out of my way to disable fishing labours on migrants. This meant that my fisher dwarf had no work, and spent all his time in my dining room, socialising with the other idlers. Naturally, he was quite popular. His death was not very well received by the dwarves. I experienced my first fort destroying tantrum spiral.
So many people died, and the floodgate got deconstructed and the fort began to slowly fill with water. The last survivors where an emergency squad of two standing outside the inaccessible fort and one baby (the child of my favourite dwarves, the only ones with furniture to call their own) surrounded by misama and puddles inside. Eventually, one recruit berserked and the other died, and the baby quickly followed suit. The fort crumbled to its end.
As for the reason this is a "Urist, you fool!" moment as opposed to just being result of my poor planning, it's because I had attempted to save my poor dwarves. The plan was simple, really. Dig a small tunnel to the outside of the hill I had made my entrance from, just 5-6 urists long, to save some dwarves form the doomed cave they were living in and start anew, surviving til the next migrant wave arrived. One miner was killed in the spiral, but I had one more, and he was fairly content, despite his situation, and he could surely dig the tunnel, right?
Wrong. He just stood there, surrounded in filth and water, til he sucumbed to hunger on his way to finally start digging the tunnel. He could have saved them. But. He. Just. Stood. There.
I know my chances of survival were slim, and that was my fault, but he robbed me of my only hope, small as it was.
It was a thoroughly enjoyable and educational experience, and for that I'm glad, but I would have liked to try and salvage a wrecked fort without reclaiming, as I had never done that before. All in all, I had FUN.