So, I tried playing a little bit more over the weekend. Specifically, on Thursday.
What happened next is a series of events so embarassing that I feel slightly hesitant to call myself a Dwarf Fortress Master (but I still do). So I'm going to tell them to you so you can laugh at me.
Immediately after I began playing, I began filling the pit that I had dug into the aquifer with magma, so that I could proceed with a magma penetration of the aquifer. I poured just enough in to seal the ring I had dug directly into the first aquifer layer with obsidian. My logic was, at the time, that I could pour more magma once I had dug out the rest of the aquifer, as at that point, no more water would be leaking in.
The magma pouring went well enough. Once enough magma evaporated, I sent in my miners to dig out the rest of the aquifer.
One miner decided to walk through 1/7 magma. I imagine this happened that he took a quick little trip to the aquifer layer before it had filled up, as I was using ramps to dig through the aquifer, and the 1/7 magma fell on top of him. Good thing he moved, else he would have been encased in cooling lava. Sadly, he was still on fire.
For reasons that aren't important, the pit that I was digging through the aquifer was currently inaccessible at the time. Fortunately for Mr. FlameyFeet, there was a worker in the pit with him, which means that if I acted quickly enough, I could have saved him from a firey death. I tossed my other pick down into the pit, I enabled mining on the worker, I placed the ramp designations... and the worker picked the wrong one to dig first. Mr. FlameyFeet was immolated. I stopped his corpse from burning, for all the good it did me. Interesting thing, though; if you manage to extinguish a flaming corpse, it will still be blinking red and orange and yellow. You learn something new everyday.
Thus, I had the new problem of a pick in the aquifer. This was hardly a problem at all; I constructed a pump and drained the aquifer long enough to recover Mr. FlameyFeet's corpse, clothes and pick.
Since this wasn't a game ending event, I decided to continue, slightly discouraged.
Things went well enough, again. Except they didn't. I resumed digging, and the other miner, Mr. DigsInWrongPlaces, had a fun surprise dropped upon him while he was digging in the aquifer. In this case, the fun surprise was not a piece of feces, but rather, a block of 1/7 magma. Mr. DigsInWrongPlaces became Mr. EncasedInCarbonite.
Notably, these two deaths were preventable, if I had channeled instead of ramped.
I had the new problem of a pick stuck in a block of obsidian. This was hardly a problem at all, as I dug out the block, constructed the pump, and retrieved the pick. Oddly enough, I couldn't recover Mr. EncasedInCarbonite's corpse, as it was in the phantom zone or somewhere else irretrievable.
Since this was not a game ending event, I decided to continue.
The traders arrived. I deliberately took all their stuff by deconstructing the depot. This would have important consequences in spring, which arrived fairly quickly. Migrants decided to not come. Apparently, stealing the caravan's treasures does bad things for immigration.
It is important to note, that at this point, I still hadn't pierced through the aquifer. However, I continued on.
Sometime during summer, as I was about to pour the second bout of magma on the second aquifer layer, my pump operator was being interrupted by fire imps, one of whom jumped out of the magma pipe. I sent in my woodcutter/axedwarf, who fortunately for me, had not died yet, after the fire imp. The fire imp was slayed quickly, but not before he missed the woodcutter with a fireball. Thus, a brush fire was started.
The brush fire killed everyone. This was entirely accidental and was in no way preventable and was most certainly not deliberately allowed so that I could restart the map over once everyone had died.
So that's what's happened so far. I would've started over, but I didn't have access to the Internet over the whole weekend, so I couldn't re-download the map. This is also why you're hearing about this now, instead of on Thursday, when it happened.
All of these problems were completely foreseeable and preventable, but I was really, really sick at the time, so my judgment was likely disproportionately impaired, causing all of these problems, relative to how much it actually was.
tl;dr: Fuck this, I'm starting over.