Well that didn't go as well as expected.
The embark is absolutely fantastic except for a couple things. There is magma, iron, a huge flux layer (needed in steel manufacture), plentiful metals, gems, and anything else a dwarf could want.
Except for water. This would be a minor problem, but there's also absolutely no vegetation, at least none that can be brewed. So much worse, there's no water and no alcohol either. I had brought a fair amount, anticipating at least the "sparse" vegetation advertised on the embark screen but instead there's absolutely none.
I should have hopped on this immediately but decided to go for the magma first. However, that operation became somewhat complicated due to dorf logic. I needed a wall built before I filled the magma reservoirs for the forges, but they kept building it with them on the other side of it or by the time the wall got built they had decided to drop all the picks and tools on the other side despite there being a stockpile for them or otherwise doing suicidal things. Anyway, everyone became dehydrated before I finished.
So I decided to go for the caverns, since despite designating every square in sight for plant gathering, and fruit gathering zones where there appeared to be berries available, and turning this task on for everyone, nothing appeared to be brewable. The only option was finding water. Breaching the caverns early is dangerous though.
And worse, by the time I did breach the first caverns, which had water, three dwarves had died of dehydration. Everyone else drank their fill, though, so I decided to finish the magma reservoir. All I needed for that was to dig one square and then build the forges and smelters, and everything should be hunky dory.
Migrants showed up and brought our total back to six.
It kind of worried me to leave the cavern layer open but there was really no choice at this point. I also built a trade depot for the upcoming outpost liaison visit.
Now was time to secure the caverns and set up some kind of water source, maybe by bucket brigade, to be able to close off the caverns again. And muddy some stone for a makeshift farm.
And then a bunch of trolls showed up, wrecked the entire fort and the trade depot right before the dwarven caravan showed up.
So we were back to five, and with no way to purchase anything from the caravan we'd been desperately waiting for, without a trade depot.
That would be bad enough but then the fatal thing isn't that everyone is dead. It's that everyone is an absolute idiot and are "fighting" an unconscious troll but somehow can't kill it but are locked into "fighting" it anyway, for a month straight.
So a quick poll. The first option is to just see how everyone dies and/or just give up and then reclaim the fort. I don't think this is worth it. Reclaims are buggy as hell for one thing.
The second is to just take a mulligan and do the embark again. I could probably breach the cavern early and possibly in a way that lets me leak out some water (maybe by digging fortifications instead of digging in to the cavern) for a well and a farm. Then do the magma again. The "cheaty" issue here is I'd be using information I gained on the failed attempt so it's a sort of scumming.
And a third is the imo entirely unacceptable option of doing something like using dfhack to kidnap one of the dwarven caravan dwarves and just having them kill the trolls. Way too cheesy.
And the fourth is just to do another world gen. As much as I like this embark, there are an infinite number of possible others. I started early in case this happened anyway. I'm leaning toward the last.