https://rpgcodex.net/forums/index.php?threads/underrail-the-incline-awakens.105387/page-495#post-6427787
https://i3.kym-cdn.com/photos/images/newsfeed/000/562/544/0b4.jpg
I thought he was joking, but looks like codexers took his post at face value.
Anyways, saving the sormirbaeren was never an option. Here's why. I haven't seen any players reaching this conclusion yet, so it's definitely going to be spoilery.
Sormirbaeren are to Flottsormir what tchortlings (tchortbaeren) are to Tchort.
They're Serpentborn and Tchortborn in a quite literal sense. Less literally in the cases of normal sormirbaeren villagers and tchortists, but those groups are also analogues of each other. Unwitting, subtly controlled human pawns. Raw material.
If you talk with Yngwar after Deep Caverns and draw the Institute to him, you get a bit of discussion on the similaries of tchortists and his people. Tchortbaeren is the word he uses. The similarities of their natures are further enforced by the behavior of tchortlings and sormirbaeren once the link to their deity is severed - both fly into bloody rage. You get to see this in-game with tchortlings and the sormirbaeren psionics becoming permanently enraged, and sormirbaeren also get the aforementioned ending slide. ("The destruction of the Shadowlith fragment evoke bloodthirsty madness in the Sormirbaeren, and in their mutual butchery they spared no one." and "The lights turned dim, the villages fell quiet but for an occasional painful cry, and the northern coasts of the Black Sea became redder than they'd ever been.") Also, it seems to me that Oyensorm (Serpent's Eyes) is a very apparent analogue of the Mouth of Tchort. Leviathans really work in similar patterns when it comes to using humans, don't they?
You could say that this whole Expedition is yet another "Deep Caverns" and you fight the "tchortlings" of another, more distant Leviathan.
But not only that, we also get to see the Godmen/Leviathans proxy war playing out right before our eyes. Shadowlith doing its thing and Glowing Canine having appeared at a later date to interfere. And then we have Yngwar shedding Shadowlith's influence with the Glowing Canine's help... man, just what is he and what is his role in all this?
edit: whoops, post got cut off by styg's forum bugs.
Really? I was able to get something approximating a good ending, where they were defeated but their society grew peaceful. The subtext of the scene implies that they are better off without the shadowlith. The exact slides can be seen here:
https://imgur.com/a/6d5tgyPI got this ending by staying with Aegis, and destroyed both the shadowlith and its shard in the Sormirbaeren temple. I killed a lot of them, both those who attacked the camp and their ambushes outside the geothermal plant and JSHQ. However, when in their village and graveyard, I attacked no civilians, and stealthed/ran past all the guards. The only ones I killed were the priests and the guards inside the temple, who I didn't object to killing since they were clearly complicit in exposing the population to an empirically corrupting influence.
I've still got the save file if you'd like it.