As for the "pure survival" sandbox mod, it'll give you freedom to roam the evolving world and complete tasks as you please. Expect new tools that measure and score progress - how long you keep certain characters alive, for example, how effective you are at gathering supplies, and how well you maintain the community's health.
What annoyed me about SoD was the fact that to get certain achievments you had die twice and kill another survivor. Yet there were no achievments for going through the game without losing a survivor.
- Spoiler Alert -
That's because it is impossible to go through the story without losing a survivor, as there are two survivors (Erik and the Pastor) who HAVE to die, not counting those at the ranger station at the beginning of the game. Well, technically one, as Erik is never officially part of your group.
- End Spoiler -
I suppose they could have had an achievement for not ever losing a playable survivor, though. Maybe that's one that they can add in DLC…
I'm not sick, I'm twisted. Sick makes it sound like there's a cure.