There's an underground water sea on the way of another cave-in. To cut it off the map edge dwarves dug a long magma-feeding channel through the whole map, there are two short aqueducts built over the perimeter of the future cave-in:
On the way of yet another cave-in there are demons hanging out in the air inside drained magma sea. It's impossible to collapse the ceiling over their heads because all the stone all the way up already dug out. So dwarves dug out the top of the perimeter and therefore established freezing temperatures everywhere on the perimeter all the way down. Somebody poured a bucket of water and created the thing to collapse over the demons:
After the thing collapsed I found out that creatures smashed onto the magma sea bottom by collapsed ceiling, those creatures disappear as well as collapsing rocks.
Dwarves shoot railguns again. I found out that the invisible walls with which the missiles collide, those virtual walls are located in different places in different times:
Those numbers are distances from fallen cages to appropriate edges of the map: 0, 48, 82, 86. Those numbers are distances from the cannons to the cages fallen on the ground: 32, 36, 70, 87, 118. Big numbers in the first list and small numbers in the second one probably mean that those missiles lost horizontal speed due to numerous collisions with other missiles.
Probably the last caravan arriving in the underground trade depot:
The next caravan will probably trade in the sky.
One of the cannons suddenly made a large plume of smoke:
It's because a fire imp sitting in a missile survived the shot, got free and now is running around desperately over the ship:
You can see a bugbat in the corner of the photo.
Another cave-in bared the refuse stockpile, the earth stinks right to the stars:
The fort is 106 years old:
Archers training in the sky gyms: