I had a perfect, Joyous Wilds embark with everything, except maybe flux. I just started dealing with aquifers, and a single-tile deep one was the end of my fort. I had quickly set up fishing and a still and began work on the cave-in plug, and got that far, but it didn't actually collapse. It didn't have any supports, but there was still land above the plug. I removed all connection from the plug to the above land by channeling above and below the plug and removing the final floor, but there was no cave-in. I went to channel an extra area above the plug, and my miner chose the worst possible way to do so, after one of the two died by falling into the aquifer. He fell and also drowned.
gg aquifer, gg.
I don't have the save. I really want to reclaim, but isn't that kind of a hassle to complete? What with everything getting thrown about and the possible migration of beasts that need slaying (the river otters hadn't given me trouble yet). It was such a good embark, too. Well, maybe it lacked in aboveground plants, making lumber hard to come by, but still, it's better than what I normally get.
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That's what I get for using LNP I guess... Cave Ins were off the whole time. I could have had a surviving miner, too. Oh well, I can reclaim now. I really shouldn't use LNP anymore, but I like the tools it comes with and it makes installing graphics easy, so... argh.