recently I've been obsessing over mist-producing machines, and in the process I've noticed something: Mist makes dwarves insanely happy. In my current fort, all my dwarves are Ecstatic, all the time. this might not be so unusual, until you consider the following:
They have no beds
No chairs
No tables
No booze
No prepared food
No rooms
No coffins
etc etc.
basically, if it can be neglected, I've neglected it. In addition, every few months a few dwarves are killed by goblin ambushes, which I do absolutely nothing about. I simply let the goblins slaughter freely, and wait until enough of my civilian dwarves fight back on their own to get the ambush to leave. the corpses of my dwarves are left to rot.
Besides 'talking with friends' and 'admiring a fine ___' (usually the screwpumps that make the mist), the only thing causing positive thoughts in my fort is mist.
The average dwarf's thoughts look something like this:
Urist McLovesTheShitOutOfWaterfalls has been ecstatic lately. He talked with a friend lately. He lost a friend to tragedy recently. He was forced to endure the decay of a friend recently. He slept in the dirt recently. He complained about the lack of chairs lately. He was accosted by terrible vermin. He was disgusted by a miasma lately. He was comforted by a lovely waterfall recently.
So by all rights my dwarves should be blasting linkin park on loop or strangling eachother out of pure rage and despair. but apparently a meeting area with a mist machine going makes them so damned happy they can endure virtually anything.
This leads me to believe there's either a bug or simple unintended design with the way mist confers happiness onto dwarves that's causing them to get way more of a happiness boost than is intended. The first possibility that comes to mind is that they get the happy thought from seeing mist every single time they touch a tile of a mist, which means that spending even a short time around a waterfall is going to rack up huge happiness boosts.
- as an additional test, I just executed half my fortress' population simultaneously. several dwarves dropped to miserable. after less than a month of chillin in the waterfall room, they're all back up to ecstatic.