Been quite a while since I played it last, but I LOVE Dwarf Fortess. Without a doubt the best game ever in my book. Just love the how the dwarves all seem to get their own identity and personality after a while.
I'm far from good at it, usually don't last very long, but losing is fun. Right?
I've had so many fun and awesome moments in DF, mostly when my fortress goes to hell it always seems to be in some sort of hilarious accident or along those lines. My best moment however must have been on the best fortress I ever made. I started out at the bottom of a volcano so the first 5 or 6 layers of the mountain was nothing but Obsidian, so I traded very well with tools, weapons and jewelry made by Obsidian as it fetched a very good price from the caravans.
My infrastructure and food production was good, I had engravings, good space and personal belongings in every dwarves quarters and everyone was content.
Then one night right after a caravan left my fortress one of my farmers went into a 'weird mood', locked himself in a smithy and started demanding some strange stuff I could not get my hands on. So I thought, ah well, just let him rot in there I can't get that anyway. After a few days, if not weeks, of going totally insane in there without food or beer, the Farmer slams the door open runs down the hallway and kicks a cat right into the wall so it dies. He then proceeds to pick a fight with two miners and he gets killed in the fight.
Good I though, that's that dealt with. One less dwarf, but at least no disaster. But stuff never go as you think it will in DF, does it? When the cat owner found out his cat was dead he went mental and killed another dwarf and his child. This in turn made the mother go berserk and I was stuck in a tantrum circle with my whole fortress tearing itself down. Everyone fighting everyone!
In the end all I had left was a little child and two cats. Everything else was dead, blood, vomit and miasma everywhere. I laughed till my stomach hurt from all the chaos. Good times.