Well fuck moments #3
Had a sweet statue garden in the middle of my fort, and I thought it would be awesome if I had rivers of water and magma making paths through the hall. I set the whole thing up, and then figure the coolest centerpiece would be an artifact statue surrounded by a ring of gold statues, surrounded by a moat of magma.
So I dig out the magma level, carefully set up a flood gate so I can turn it off, wait for the magma to fill up the level and then carve out the paths for the river.
Of course, I completely forget leaving something holding the statue-island up, and the whole 5 statue ensemble crashes into the 7 deep magma basin setting fire to half of my population.
It gets better! So much magma was knocked up that it sent a river of magma flooding down my two main staircases into the depths of the fort and the bottom 5 levels of the fort get splattered with magma. I decide... shit, what can I do to fix this, and turn off the floodgate and decide to wait for everything to harden and to cool off so I can send the repair squad in.
Then it gets WAY better. I only notice an hour later when for some reason the frame rate is still in the 15s. The total weight of the 5 statue island ensemble was heavy enough to punch a hole down through the floor the z level below, and ended up emptying hundreds of squares worth of magma into my crypts, prison, hospital, mines, commoner residences and caves.
Turned into a sad, dad frame rate death for that forth, luckily only melted 60% of the population.