I spent most of my day off engineering a fabulous fortress. It featured fountains - five three story tall spires of rock that were supposed to pour water out of their tops via overpressure. The system's design was, as far as I could tell, perfect. After spending most of my time fighting with dwarfs that ignored traffic designations - that is, all of them, randomly wandering around in the ductwork even though it lead nowhere - and finally sealing the whole thing from entry, I activated it.

The northernmost two fountains were the only ones that activated because the 'random' directions in DF used by everything from pathfinding to overpressure always favor north and east. The drainage system - which removed exactly as much water as the input system pumped in - somehow couldn't keep up. Then I watched - the system was MAKING water. The whole thing started to flood my fortress after about a minute of comforting my dwarfs with mist, lulling them into a false sense of security and making them believe their efforts weren't wasted.

Moral of the story:
Don't do ambitious things with badly buggy alpha software.

I'm done for now. This was the only challenge DF could offer me, and it failed. I'll stick to Lego for now.